Merge branch 'development' of https://github.com/0xProject/0x-monorepo into website/feature/react-16

15 files changed, 1765 insertions, 533 deletions

diff --git a/packages/contracts/test/asset_proxy/proxies.ts b/packages/contracts/test/asset_proxy/proxies.ts
index 76a020222..6031e554d 100644
--- a/packages/contracts/test/asset_proxy/proxies.ts
+++ b/packages/contracts/test/asset_proxy/proxies.ts
@@ -12,7 +12,7 @@ import { ERC20ProxyContract } from '../../generated_contract_wrappers/erc20_prox
 import { ERC721ProxyContract } from '../../generated_contract_wrappers/erc721_proxy';
 import { IAssetProxyContract } from '../../generated_contract_wrappers/i_asset_proxy';
 import { artifacts } from '../utils/artifacts';
-import { expectTransactionFailedAsync } from '../utils/assertions';
+import { expectTransactionFailedAsync, expectTransactionFailedWithoutReasonAsync } from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
 import { ERC20Wrapper } from '../utils/erc20_wrapper';
@@ -99,6 +99,17 @@ describe('Asset Transfer Proxies', () => {
         await blockchainLifecycle.revertAsync();
     });
     describe('Transfer Proxy - ERC20', () => {
+        it('should revert if undefined function is called', async () => {
+            const undefinedSelector = '0x01020304';
+            await expectTransactionFailedWithoutReasonAsync(
+                web3Wrapper.sendTransactionAsync({
+                    from: owner,
+                    to: erc20Proxy.address,
+                    value: constants.ZERO_AMOUNT,
+                    data: undefinedSelector,
+                }),
+            );
+        });
         describe('transferFrom', () => {
             it('should successfully transfer tokens', async () => {
                 // Construct ERC20 asset data
@@ -219,6 +230,17 @@ describe('Asset Transfer Proxies', () => {
     });
 
     describe('Transfer Proxy - ERC721', () => {
+        it('should revert if undefined function is called', async () => {
+            const undefinedSelector = '0x01020304';
+            await expectTransactionFailedWithoutReasonAsync(
+                web3Wrapper.sendTransactionAsync({
+                    from: owner,
+                    to: erc721Proxy.address,
+                    value: constants.ZERO_AMOUNT,
+                    data: undefinedSelector,
+                }),
+            );
+        });
         describe('transferFrom', () => {
             it('should successfully transfer tokens', async () => {
                 // Construct ERC721 asset data
diff --git a/packages/contracts/test/exchange/core.ts b/packages/contracts/test/exchange/core.ts
index bc2bad749..3bb71b58f 100644
--- a/packages/contracts/test/exchange/core.ts
+++ b/packages/contracts/test/exchange/core.ts
@@ -1,6 +1,6 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
 import { assetDataUtils, orderHashUtils } from '@0xproject/order-utils';
-import { RevertReason, SignedOrder } from '@0xproject/types';
+import { RevertReason, SignatureType, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
@@ -14,6 +14,8 @@ import { DummyNoReturnERC20TokenContract } from '../../generated_contract_wrappe
 import { ERC20ProxyContract } from '../../generated_contract_wrappers/erc20_proxy';
 import { ERC721ProxyContract } from '../../generated_contract_wrappers/erc721_proxy';
 import { ExchangeCancelEventArgs, ExchangeContract } from '../../generated_contract_wrappers/exchange';
+import { ReentrantERC20TokenContract } from '../../generated_contract_wrappers/reentrant_erc20_token';
+import { TestStaticCallReceiverContract } from '../../generated_contract_wrappers/test_static_call_receiver';
 import { artifacts } from '../utils/artifacts';
 import { expectTransactionFailedAsync } from '../utils/assertions';
 import { getLatestBlockTimestampAsync, increaseTimeAndMineBlockAsync } from '../utils/block_timestamp';
@@ -41,9 +43,12 @@ describe('Exchange core', () => {
     let zrxToken: DummyERC20TokenContract;
     let erc721Token: DummyERC721TokenContract;
     let noReturnErc20Token: DummyNoReturnERC20TokenContract;
+    let reentrantErc20Token: ReentrantERC20TokenContract;
     let exchange: ExchangeContract;
     let erc20Proxy: ERC20ProxyContract;
     let erc721Proxy: ERC721ProxyContract;
+    let maliciousWallet: TestStaticCallReceiverContract;
+    let maliciousValidator: TestStaticCallReceiverContract;
 
     let signedOrder: SignedOrder;
     let erc20Balances: ERC20BalancesByOwner;
@@ -109,6 +114,18 @@ describe('Exchange core', () => {
             constants.AWAIT_TRANSACTION_MINED_MS,
         );
 
+        maliciousWallet = maliciousValidator = await TestStaticCallReceiverContract.deployFrom0xArtifactAsync(
+            artifacts.TestStaticCallReceiver,
+            provider,
+            txDefaults,
+        );
+        reentrantErc20Token = await ReentrantERC20TokenContract.deployFrom0xArtifactAsync(
+            artifacts.ReentrantERC20Token,
+            provider,
+            txDefaults,
+            exchange.address,
+        );
+
         defaultMakerAssetAddress = erc20TokenA.address;
         defaultTakerAssetAddress = erc20TokenB.address;
 
@@ -135,6 +152,26 @@ describe('Exchange core', () => {
             signedOrder = await orderFactory.newSignedOrderAsync();
         });
 
+        const reentrancyTest = (functionNames: string[]) => {
+            _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                const description = `should not allow fillOrder to reenter the Exchange contract via ${functionName}`;
+                it(description, async () => {
+                    signedOrder = await orderFactory.newSignedOrderAsync({
+                        makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                    });
+                    await web3Wrapper.awaitTransactionSuccessAsync(
+                        await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                        constants.AWAIT_TRANSACTION_MINED_MS,
+                    );
+                    await expectTransactionFailedAsync(
+                        exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
+                        RevertReason.TransferFailed,
+                    );
+                });
+            });
+        };
+        describe('fillOrder reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
         it('should throw if signature is invalid', async () => {
             signedOrder = await orderFactory.newSignedOrderAsync({
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
@@ -161,6 +198,51 @@ describe('Exchange core', () => {
                 RevertReason.OrderUnfillable,
             );
         });
+
+        it('should revert if `isValidSignature` tries to update state when SignatureType=Wallet', async () => {
+            const maliciousMakerAddress = maliciousWallet.address;
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await erc20TokenA.setBalance.sendTransactionAsync(
+                    maliciousMakerAddress,
+                    constants.INITIAL_ERC20_BALANCE,
+                ),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await maliciousWallet.approveERC20.sendTransactionAsync(
+                    erc20TokenA.address,
+                    erc20Proxy.address,
+                    constants.INITIAL_ERC20_ALLOWANCE,
+                ),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            signedOrder = await orderFactory.newSignedOrderAsync({
+                makerAddress: maliciousMakerAddress,
+                makerFee: constants.ZERO_AMOUNT,
+            });
+            signedOrder.signature = `0x0${SignatureType.Wallet}`;
+            await expectTransactionFailedAsync(
+                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
+                RevertReason.WalletError,
+            );
+        });
+
+        it('should revert if `isValidSignature` tries to update state when SignatureType=Validator', async () => {
+            const isApproved = true;
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await exchange.setSignatureValidatorApproval.sendTransactionAsync(
+                    maliciousValidator.address,
+                    isApproved,
+                    { from: makerAddress },
+                ),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            signedOrder.signature = `${maliciousValidator.address}0${SignatureType.Validator}`;
+            await expectTransactionFailedAsync(
+                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
+                RevertReason.ValidatorError,
+            );
+        });
     });
 
     describe('Testing exchange of ERC20 tokens with no return values', () => {
@@ -448,7 +530,7 @@ describe('Exchange core', () => {
                 // HACK(albrow): We need to hardcode the gas estimate here because
                 // the Geth gas estimator doesn't work with the way we use
                 // delegatecall and swallow errors.
-                gas: 490000,
+                gas: 600000,
             });
 
             const newBalances = await erc20Wrapper.getBalancesAsync();
diff --git a/packages/contracts/test/exchange/internal.ts b/packages/contracts/test/exchange/internal.ts
index 67d1d2d2c..dc2c5fbe0 100644
--- a/packages/contracts/test/exchange/internal.ts
+++ b/packages/contracts/test/exchange/internal.ts
@@ -1,6 +1,7 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
 import { Order, RevertReason, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
+import * as chai from 'chai';
 import * as _ from 'lodash';
 
 import { TestExchangeInternalsContract } from '../../generated_contract_wrappers/test_exchange_internals';
@@ -16,6 +17,8 @@ import { FillResults } from '../utils/types';
 import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
+const expect = chai.expect;
+
 const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 
 const MAX_UINT256 = new BigNumber(2).pow(256).minus(1);
@@ -43,26 +46,11 @@ const emptySignedOrder: SignedOrder = {
 
 const overflowErrorForCall = new Error(RevertReason.Uint256Overflow);
 
-async function referenceGetPartialAmountAsync(
-    numerator: BigNumber,
-    denominator: BigNumber,
-    target: BigNumber,
-): Promise<BigNumber> {
-    const invalidOpcodeErrorForCall = new Error(await getInvalidOpcodeErrorMessageForCallAsync());
-    const product = numerator.mul(target);
-    if (product.greaterThan(MAX_UINT256)) {
-        throw overflowErrorForCall;
-    }
-    if (denominator.eq(0)) {
-        throw invalidOpcodeErrorForCall;
-    }
-    return product.dividedToIntegerBy(denominator);
-}
-
 describe('Exchange core internal functions', () => {
     let testExchange: TestExchangeInternalsContract;
-    let invalidOpcodeErrorForCall: Error | undefined;
     let overflowErrorForSendTransaction: Error | undefined;
+    let divisionByZeroErrorForCall: Error | undefined;
+    let roundingErrorForCall: Error | undefined;
 
     before(async () => {
         await blockchainLifecycle.startAsync();
@@ -79,11 +67,86 @@ describe('Exchange core internal functions', () => {
         overflowErrorForSendTransaction = new Error(
             await getRevertReasonOrErrorMessageForSendTransactionAsync(RevertReason.Uint256Overflow),
         );
-        invalidOpcodeErrorForCall = new Error(await getInvalidOpcodeErrorMessageForCallAsync());
+        divisionByZeroErrorForCall = new Error(RevertReason.DivisionByZero);
+        roundingErrorForCall = new Error(RevertReason.RoundingError);
     });
     // Note(albrow): Don't forget to add beforeEach and afterEach calls to reset
     // the blockchain state for any tests which modify it!
 
+    async function referenceIsRoundingErrorFloorAsync(
+        numerator: BigNumber,
+        denominator: BigNumber,
+        target: BigNumber,
+    ): Promise<boolean> {
+        if (denominator.eq(0)) {
+            throw divisionByZeroErrorForCall;
+        }
+        if (numerator.eq(0)) {
+            return false;
+        }
+        if (target.eq(0)) {
+            return false;
+        }
+        const product = numerator.mul(target);
+        const remainder = product.mod(denominator);
+        const remainderTimes1000 = remainder.mul('1000');
+        const isError = remainderTimes1000.gte(product);
+        if (product.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        if (remainderTimes1000.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        return isError;
+    }
+
+    async function referenceIsRoundingErrorCeilAsync(
+        numerator: BigNumber,
+        denominator: BigNumber,
+        target: BigNumber,
+    ): Promise<boolean> {
+        if (denominator.eq(0)) {
+            throw divisionByZeroErrorForCall;
+        }
+        if (numerator.eq(0)) {
+            return false;
+        }
+        if (target.eq(0)) {
+            return false;
+        }
+        const product = numerator.mul(target);
+        const remainder = product.mod(denominator);
+        const error = denominator.sub(remainder).mod(denominator);
+        const errorTimes1000 = error.mul('1000');
+        const isError = errorTimes1000.gte(product);
+        if (product.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        if (errorTimes1000.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        return isError;
+    }
+
+    async function referenceSafeGetPartialAmountFloorAsync(
+        numerator: BigNumber,
+        denominator: BigNumber,
+        target: BigNumber,
+    ): Promise<BigNumber> {
+        if (denominator.eq(0)) {
+            throw divisionByZeroErrorForCall;
+        }
+        const isRoundingError = await referenceIsRoundingErrorFloorAsync(numerator, denominator, target);
+        if (isRoundingError) {
+            throw roundingErrorForCall;
+        }
+        const product = numerator.mul(target);
+        if (product.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        return product.dividedToIntegerBy(denominator);
+    }
+
     describe('addFillResults', async () => {
         function makeFillResults(value: BigNumber): FillResults {
             return {
@@ -158,19 +221,22 @@ describe('Exchange core internal functions', () => {
             // in any mathematical operation in either the reference TypeScript
             // implementation or the Solidity implementation of
             // calculateFillResults.
+            const makerAssetFilledAmount = await referenceSafeGetPartialAmountFloorAsync(
+                takerAssetFilledAmount,
+                orderTakerAssetAmount,
+                otherAmount,
+            );
+            const order = makeOrder(otherAmount, orderTakerAssetAmount, otherAmount, otherAmount);
+            const orderMakerAssetAmount = order.makerAssetAmount;
             return {
-                makerAssetFilledAmount: await referenceGetPartialAmountAsync(
-                    takerAssetFilledAmount,
-                    orderTakerAssetAmount,
-                    otherAmount,
-                ),
+                makerAssetFilledAmount,
                 takerAssetFilledAmount,
-                makerFeePaid: await referenceGetPartialAmountAsync(
-                    takerAssetFilledAmount,
-                    orderTakerAssetAmount,
+                makerFeePaid: await referenceSafeGetPartialAmountFloorAsync(
+                    makerAssetFilledAmount,
+                    orderMakerAssetAmount,
                     otherAmount,
                 ),
-                takerFeePaid: await referenceGetPartialAmountAsync(
+                takerFeePaid: await referenceSafeGetPartialAmountFloorAsync(
                     takerAssetFilledAmount,
                     orderTakerAssetAmount,
                     otherAmount,
@@ -193,60 +259,158 @@ describe('Exchange core internal functions', () => {
         );
     });
 
-    describe('getPartialAmount', async () => {
-        async function testGetPartialAmountAsync(
+    describe('getPartialAmountFloor', async () => {
+        async function referenceGetPartialAmountFloorAsync(
             numerator: BigNumber,
             denominator: BigNumber,
             target: BigNumber,
         ): Promise<BigNumber> {
-            return testExchange.publicGetPartialAmount.callAsync(numerator, denominator, target);
+            if (denominator.eq(0)) {
+                throw divisionByZeroErrorForCall;
+            }
+            const product = numerator.mul(target);
+            if (product.greaterThan(MAX_UINT256)) {
+                throw overflowErrorForCall;
+            }
+            return product.dividedToIntegerBy(denominator);
+        }
+        async function testGetPartialAmountFloorAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<BigNumber> {
+            return testExchange.publicGetPartialAmountFloor.callAsync(numerator, denominator, target);
         }
         await testCombinatoriallyWithReferenceFuncAsync(
-            'getPartialAmount',
-            referenceGetPartialAmountAsync,
-            testGetPartialAmountAsync,
+            'getPartialAmountFloor',
+            referenceGetPartialAmountFloorAsync,
+            testGetPartialAmountFloorAsync,
             [uint256Values, uint256Values, uint256Values],
         );
     });
 
-    describe('isRoundingError', async () => {
-        async function referenceIsRoundingErrorAsync(
+    describe('getPartialAmountCeil', async () => {
+        async function referenceGetPartialAmountCeilAsync(
             numerator: BigNumber,
             denominator: BigNumber,
             target: BigNumber,
-        ): Promise<boolean> {
-            const product = numerator.mul(target);
+        ): Promise<BigNumber> {
             if (denominator.eq(0)) {
-                throw invalidOpcodeErrorForCall;
-            }
-            const remainder = product.mod(denominator);
-            if (remainder.eq(0)) {
-                return false;
+                throw divisionByZeroErrorForCall;
             }
-            if (product.greaterThan(MAX_UINT256)) {
+            const product = numerator.mul(target);
+            const offset = product.add(denominator.sub(1));
+            if (offset.greaterThan(MAX_UINT256)) {
                 throw overflowErrorForCall;
             }
-            if (product.eq(0)) {
-                throw invalidOpcodeErrorForCall;
+            const result = offset.dividedToIntegerBy(denominator);
+            if (product.mod(denominator).eq(0)) {
+                expect(result.mul(denominator)).to.be.bignumber.eq(product);
+            } else {
+                expect(result.mul(denominator)).to.be.bignumber.gt(product);
             }
-            const remainderTimes1000000 = remainder.mul('1000000');
-            if (remainderTimes1000000.greaterThan(MAX_UINT256)) {
+            return result;
+        }
+        async function testGetPartialAmountCeilAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<BigNumber> {
+            return testExchange.publicGetPartialAmountCeil.callAsync(numerator, denominator, target);
+        }
+        await testCombinatoriallyWithReferenceFuncAsync(
+            'getPartialAmountCeil',
+            referenceGetPartialAmountCeilAsync,
+            testGetPartialAmountCeilAsync,
+            [uint256Values, uint256Values, uint256Values],
+        );
+    });
+
+    describe('safeGetPartialAmountFloor', async () => {
+        async function testSafeGetPartialAmountFloorAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<BigNumber> {
+            return testExchange.publicSafeGetPartialAmountFloor.callAsync(numerator, denominator, target);
+        }
+        await testCombinatoriallyWithReferenceFuncAsync(
+            'safeGetPartialAmountFloor',
+            referenceSafeGetPartialAmountFloorAsync,
+            testSafeGetPartialAmountFloorAsync,
+            [uint256Values, uint256Values, uint256Values],
+        );
+    });
+
+    describe('safeGetPartialAmountCeil', async () => {
+        async function referenceSafeGetPartialAmountCeilAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<BigNumber> {
+            if (denominator.eq(0)) {
+                throw divisionByZeroErrorForCall;
+            }
+            const isRoundingError = await referenceIsRoundingErrorCeilAsync(numerator, denominator, target);
+            if (isRoundingError) {
+                throw roundingErrorForCall;
+            }
+            const product = numerator.mul(target);
+            const offset = product.add(denominator.sub(1));
+            if (offset.greaterThan(MAX_UINT256)) {
                 throw overflowErrorForCall;
             }
-            const errPercentageTimes1000000 = remainderTimes1000000.dividedToIntegerBy(product);
-            return errPercentageTimes1000000.greaterThan('1000');
+            const result = offset.dividedToIntegerBy(denominator);
+            if (product.mod(denominator).eq(0)) {
+                expect(result.mul(denominator)).to.be.bignumber.eq(product);
+            } else {
+                expect(result.mul(denominator)).to.be.bignumber.gt(product);
+            }
+            return result;
+        }
+        async function testSafeGetPartialAmountCeilAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<BigNumber> {
+            return testExchange.publicSafeGetPartialAmountCeil.callAsync(numerator, denominator, target);
+        }
+        await testCombinatoriallyWithReferenceFuncAsync(
+            'safeGetPartialAmountCeil',
+            referenceSafeGetPartialAmountCeilAsync,
+            testSafeGetPartialAmountCeilAsync,
+            [uint256Values, uint256Values, uint256Values],
+        );
+    });
+
+    describe('isRoundingErrorFloor', async () => {
+        async function testIsRoundingErrorFloorAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<boolean> {
+            return testExchange.publicIsRoundingErrorFloor.callAsync(numerator, denominator, target);
         }
-        async function testIsRoundingErrorAsync(
+        await testCombinatoriallyWithReferenceFuncAsync(
+            'isRoundingErrorFloor',
+            referenceIsRoundingErrorFloorAsync,
+            testIsRoundingErrorFloorAsync,
+            [uint256Values, uint256Values, uint256Values],
+        );
+    });
+
+    describe('isRoundingErrorCeil', async () => {
+        async function testIsRoundingErrorCeilAsync(
             numerator: BigNumber,
             denominator: BigNumber,
             target: BigNumber,
         ): Promise<boolean> {
-            return testExchange.publicIsRoundingError.callAsync(numerator, denominator, target);
+            return testExchange.publicIsRoundingErrorCeil.callAsync(numerator, denominator, target);
         }
         await testCombinatoriallyWithReferenceFuncAsync(
-            'isRoundingError',
-            referenceIsRoundingErrorAsync,
-            testIsRoundingErrorAsync,
+            'isRoundingErrorCeil',
+            referenceIsRoundingErrorCeilAsync,
+            testIsRoundingErrorCeilAsync,
             [uint256Values, uint256Values, uint256Values],
         );
     });
diff --git a/packages/contracts/test/exchange/libs.ts b/packages/contracts/test/exchange/libs.ts
index 6c3305d1d..37234489e 100644
--- a/packages/contracts/test/exchange/libs.ts
+++ b/packages/contracts/test/exchange/libs.ts
@@ -71,29 +71,57 @@ describe('Exchange libs', () => {
     // combinatorial tests in test/exchange/internal. They test specific edge
     // cases that are not covered by the combinatorial tests.
     describe('LibMath', () => {
-        it('should return false if there is a rounding error of 0.1%', async () => {
-            const numerator = new BigNumber(20);
-            const denominator = new BigNumber(999);
-            const target = new BigNumber(50);
-            // rounding error = ((20*50/999) - floor(20*50/999)) / (20*50/999) = 0.1%
-            const isRoundingError = await libs.publicIsRoundingError.callAsync(numerator, denominator, target);
-            expect(isRoundingError).to.be.false();
-        });
-        it('should return false if there is a rounding of 0.09%', async () => {
-            const numerator = new BigNumber(20);
-            const denominator = new BigNumber(9991);
-            const target = new BigNumber(500);
-            // rounding error = ((20*500/9991) - floor(20*500/9991)) / (20*500/9991) = 0.09%
-            const isRoundingError = await libs.publicIsRoundingError.callAsync(numerator, denominator, target);
-            expect(isRoundingError).to.be.false();
+        describe('isRoundingError', () => {
+            it('should return true if there is a rounding error of 0.1%', async () => {
+                const numerator = new BigNumber(20);
+                const denominator = new BigNumber(999);
+                const target = new BigNumber(50);
+                // rounding error = ((20*50/999) - floor(20*50/999)) / (20*50/999) = 0.1%
+                const isRoundingError = await libs.publicIsRoundingErrorFloor.callAsync(numerator, denominator, target);
+                expect(isRoundingError).to.be.true();
+            });
+            it('should return false if there is a rounding of 0.09%', async () => {
+                const numerator = new BigNumber(20);
+                const denominator = new BigNumber(9991);
+                const target = new BigNumber(500);
+                // rounding error = ((20*500/9991) - floor(20*500/9991)) / (20*500/9991) = 0.09%
+                const isRoundingError = await libs.publicIsRoundingErrorFloor.callAsync(numerator, denominator, target);
+                expect(isRoundingError).to.be.false();
+            });
+            it('should return true if there is a rounding error of 0.11%', async () => {
+                const numerator = new BigNumber(20);
+                const denominator = new BigNumber(9989);
+                const target = new BigNumber(500);
+                // rounding error = ((20*500/9989) - floor(20*500/9989)) / (20*500/9989) = 0.011%
+                const isRoundingError = await libs.publicIsRoundingErrorFloor.callAsync(numerator, denominator, target);
+                expect(isRoundingError).to.be.true();
+            });
         });
-        it('should return true if there is a rounding error of 0.11%', async () => {
-            const numerator = new BigNumber(20);
-            const denominator = new BigNumber(9989);
-            const target = new BigNumber(500);
-            // rounding error = ((20*500/9989) - floor(20*500/9989)) / (20*500/9989) = 0.011%
-            const isRoundingError = await libs.publicIsRoundingError.callAsync(numerator, denominator, target);
-            expect(isRoundingError).to.be.true();
+        describe('isRoundingErrorCeil', () => {
+            it('should return true if there is a rounding error of 0.1%', async () => {
+                const numerator = new BigNumber(20);
+                const denominator = new BigNumber(1001);
+                const target = new BigNumber(50);
+                // rounding error = (ceil(20*50/1001) - (20*50/1001)) / (20*50/1001) = 0.1%
+                const isRoundingError = await libs.publicIsRoundingErrorCeil.callAsync(numerator, denominator, target);
+                expect(isRoundingError).to.be.true();
+            });
+            it('should return false if there is a rounding of 0.09%', async () => {
+                const numerator = new BigNumber(20);
+                const denominator = new BigNumber(10009);
+                const target = new BigNumber(500);
+                // rounding error = (ceil(20*500/10009) - (20*500/10009)) / (20*500/10009) = 0.09%
+                const isRoundingError = await libs.publicIsRoundingErrorCeil.callAsync(numerator, denominator, target);
+                expect(isRoundingError).to.be.false();
+            });
+            it('should return true if there is a rounding error of 0.11%', async () => {
+                const numerator = new BigNumber(20);
+                const denominator = new BigNumber(10011);
+                const target = new BigNumber(500);
+                // rounding error = (ceil(20*500/10011) - (20*500/10011)) / (20*500/10011) = 0.11%
+                const isRoundingError = await libs.publicIsRoundingErrorCeil.callAsync(numerator, denominator, target);
+                expect(isRoundingError).to.be.true();
+            });
         });
     });
 
diff --git a/packages/contracts/test/exchange/match_orders.ts b/packages/contracts/test/exchange/match_orders.ts
index 46b3569bd..554c456cc 100644
--- a/packages/contracts/test/exchange/match_orders.ts
+++ b/packages/contracts/test/exchange/match_orders.ts
@@ -11,6 +11,8 @@ import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dumm
 import { ERC20ProxyContract } from '../../generated_contract_wrappers/erc20_proxy';
 import { ERC721ProxyContract } from '../../generated_contract_wrappers/erc721_proxy';
 import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
+import { ReentrantERC20TokenContract } from '../../generated_contract_wrappers/reentrant_erc20_token';
+import { TestExchangeInternalsContract } from '../../generated_contract_wrappers/test_exchange_internals';
 import { artifacts } from '../utils/artifacts';
 import { expectTransactionFailedAsync } from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
@@ -20,12 +22,12 @@ import { ERC721Wrapper } from '../utils/erc721_wrapper';
 import { ExchangeWrapper } from '../utils/exchange_wrapper';
 import { MatchOrderTester } from '../utils/match_order_tester';
 import { OrderFactory } from '../utils/order_factory';
-import { ERC20BalancesByOwner, ERC721TokenIdsByOwner, OrderInfo, OrderStatus } from '../utils/types';
+import { ERC20BalancesByOwner, ERC721TokenIdsByOwner } from '../utils/types';
 import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 chaiSetup.configure();
 const expect = chai.expect;
-const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 
 describe('matchOrders', () => {
     let makerAddressLeft: string;
@@ -39,6 +41,7 @@ describe('matchOrders', () => {
     let erc20TokenB: DummyERC20TokenContract;
     let zrxToken: DummyERC20TokenContract;
     let erc721Token: DummyERC721TokenContract;
+    let reentrantErc20Token: ReentrantERC20TokenContract;
     let exchange: ExchangeContract;
     let erc20Proxy: ERC20ProxyContract;
     let erc721Proxy: ERC721ProxyContract;
@@ -60,6 +63,8 @@ describe('matchOrders', () => {
 
     let matchOrderTester: MatchOrderTester;
 
+    let testExchange: TestExchangeInternalsContract;
+
     before(async () => {
         await blockchainLifecycle.startAsync();
     });
@@ -127,23 +132,46 @@ describe('matchOrders', () => {
             }),
             constants.AWAIT_TRANSACTION_MINED_MS,
         );
+
+        reentrantErc20Token = await ReentrantERC20TokenContract.deployFrom0xArtifactAsync(
+            artifacts.ReentrantERC20Token,
+            provider,
+            txDefaults,
+            exchange.address,
+        );
+
         // Set default addresses
         defaultERC20MakerAssetAddress = erc20TokenA.address;
         defaultERC20TakerAssetAddress = erc20TokenB.address;
         defaultERC721AssetAddress = erc721Token.address;
         // Create default order parameters
-        const defaultOrderParams = {
+        const defaultOrderParamsLeft = {
             ...constants.STATIC_ORDER_PARAMS,
+            makerAddress: makerAddressLeft,
             exchangeAddress: exchange.address,
             makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
             takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
+            feeRecipientAddress: feeRecipientAddressLeft,
+        };
+        const defaultOrderParamsRight = {
+            ...constants.STATIC_ORDER_PARAMS,
+            makerAddress: makerAddressRight,
+            exchangeAddress: exchange.address,
+            makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
+            takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
+            feeRecipientAddress: feeRecipientAddressRight,
         };
         const privateKeyLeft = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(makerAddressLeft)];
-        orderFactoryLeft = new OrderFactory(privateKeyLeft, defaultOrderParams);
+        orderFactoryLeft = new OrderFactory(privateKeyLeft, defaultOrderParamsLeft);
         const privateKeyRight = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(makerAddressRight)];
-        orderFactoryRight = new OrderFactory(privateKeyRight, defaultOrderParams);
+        orderFactoryRight = new OrderFactory(privateKeyRight, defaultOrderParamsRight);
         // Set match order tester
         matchOrderTester = new MatchOrderTester(exchangeWrapper, erc20Wrapper, erc721Wrapper, zrxToken.address);
+        testExchange = await TestExchangeInternalsContract.deployFrom0xArtifactAsync(
+            artifacts.TestExchangeInternals,
+            provider,
+            txDefaults,
+        );
     });
     beforeEach(async () => {
         await blockchainLifecycle.startAsync();
@@ -157,263 +185,580 @@ describe('matchOrders', () => {
             erc721TokenIdsByOwner = await erc721Wrapper.getBalancesAsync();
         });
 
-        it('should transfer the correct amounts when orders completely fill each other', async () => {
+        it('Should transfer correct amounts when right order is fully filled and values pass isRoundingErrorFloor but fail isRoundingErrorCeil', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(17), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(98), 0),
                 feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
                 feeRecipientAddress: feeRecipientAddressRight,
             });
+            // Assert is rounding error ceil & not rounding error floor
+            // These assertions are taken from MixinMatchOrders::calculateMatchedFillResults
+            // The rounding error is derived computating how much the left maker will sell.
+            const numerator = signedOrderLeft.makerAssetAmount;
+            const denominator = signedOrderLeft.takerAssetAmount;
+            const target = signedOrderRight.makerAssetAmount;
+            const isRoundingErrorCeil = await testExchange.publicIsRoundingErrorCeil.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorCeil).to.be.true();
+            const isRoundingErrorFloor = await testExchange.publicIsRoundingErrorFloor.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorFloor).to.be.false();
             // Match signedOrderLeft with signedOrderRight
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            // Note that the left maker received a slightly better sell price.
+            // This is intentional; see note in MixinMatchOrders.calculateMatchedFillResults.
+            // Because the left maker received a slightly more favorable sell price, the fee
+            // paid by the left taker is slightly higher than that paid by the left maker.
+            // Fees can be thought of as a tax paid by the seller, derived from the sale price.
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('76.4705882352941176'), 16), // 76.47%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(0), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber('76.5306122448979591'), 16), // 76.53%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
-            // Verify left order was fully filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify right order was fully filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
-        it('should transfer the correct amounts when orders completely fill each other and taker doesnt take a profit', async () => {
+        it('Should transfer correct amounts when left order is fully filled and values pass isRoundingErrorCeil but fail isRoundingErrorFloor', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(15), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 0),
                 feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(97), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(14), 0),
                 feeRecipientAddress: feeRecipientAddressRight,
             });
-            // Store original taker balance
-            const takerInitialBalances = _.cloneDeep(erc20BalancesByOwner[takerAddress][defaultERC20MakerAssetAddress]);
+            // Assert is rounding error floor & not rounding error ceil
+            // These assertions are taken from MixinMatchOrders::calculateMatchedFillResults
+            // The rounding error is derived computating how much the right maker will buy.
+            const numerator = signedOrderRight.takerAssetAmount;
+            const denominator = signedOrderRight.makerAssetAmount;
+            const target = signedOrderLeft.takerAssetAmount;
+            const isRoundingErrorFloor = await testExchange.publicIsRoundingErrorFloor.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorFloor).to.be.true();
+            const isRoundingErrorCeil = await testExchange.publicIsRoundingErrorCeil.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorCeil).to.be.false();
             // Match signedOrderLeft with signedOrderRight
-            let newERC20BalancesByOwner: ERC20BalancesByOwner;
-            let newERC721TokenIdsByOwner: ERC721TokenIdsByOwner;
-            // prettier-ignore
-            [
-                newERC20BalancesByOwner,
-                // tslint:disable-next-line:trailing-comma
-                newERC721TokenIdsByOwner
-            ] = await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            // Note that the right maker received a slightly better purchase price.
+            // This is intentional; see note in MixinMatchOrders.calculateMatchedFillResults.
+            // Because the right maker received a slightly more favorable buy price, the fee
+            // paid by the right taker is slightly higher than that paid by the right maker.
+            // Fees can be thought of as a tax paid by the seller, derived from the sale price.
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(15), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('92.7835051546391752'), 16), // 92.78%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber('92.8571428571428571'), 16), // 92.85%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
-            );
-            // Verify left order was fully filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify right order was fully filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify taker did not take a profit
-            expect(takerInitialBalances).to.be.deep.equal(
-                newERC20BalancesByOwner[takerAddress][defaultERC20MakerAssetAddress],
+                expectedTransferAmounts,
             );
         });
 
-        it('should transfer the correct amounts when left order is completely filled and right order is partially filled', async () => {
+        it('Should give right maker a better buy price when rounding', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(16), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
                 feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(20), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(83), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(49), 0),
                 feeRecipientAddress: feeRecipientAddressRight,
             });
-            // Match orders
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            // Note:
+            // The correct price buy price for the right maker would yield (49/83) * 22 = 12.988 units
+            // of the left maker asset. This gets rounded up to 13, giving the right maker a better price.
+            // Note:
+            //  The maker/taker fee percentage paid on the right order differs because
+            //  they received different sale prices. The right maker pays a
+            //  fee slightly lower than the right taker.
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(16), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('26.5060240963855421'), 16), // 26.506%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber('26.5306122448979591'), 16), // 26.531%
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
-            // Verify left order was fully filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify right order was partially filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
         });
 
-        it('should transfer the correct amounts when right order is completely filled and left order is partially filled', async () => {
+        it('Should give left maker a better sell price when rounding', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(12), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(97), 0),
                 feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(89), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
                 feeRecipientAddress: feeRecipientAddressRight,
             });
-            // Match orders
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            // Note:
+            //  The maker/taker fee percentage paid on the left order differs because
+            //  they received different sale prices. The left maker pays a fee
+            //  slightly lower than the left taker.
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(11), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(89), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('91.6666666666666666'), 16), // 91.6%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(89), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber('91.7525773195876288'), 16), // 91.75%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
-            // Verify left order was partially filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
-            // Verify right order was fully filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
-        it('should transfer the correct amounts when consecutive calls are used to completely fill the left order', async () => {
+        it('Should transfer correct amounts when right order fill amount deviates from amount derived by `Exchange.fillOrder`', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1000), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1005), 0),
                 feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2126), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1063), 0),
+                feeRecipientAddress: feeRecipientAddressRight,
+            });
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1000), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1005), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                // Notes:
+                //  i.
+                //    The left order is fully filled by the right order, so the right maker must sell 1005 units of their asset to the left maker.
+                //    By selling 1005 units, the right maker should theoretically receive 502.5 units of the left maker's asset.
+                //    Since the transfer amount must be an integer, this value must be rounded down to 502 or up to 503.
+                //  ii.
+                //    If the right order were filled via `Exchange.fillOrder` the respective fill amounts would be [1004, 502] or [1006, 503].
+                //    It follows that we cannot trigger a sale of 1005 units of the right maker's asset through `Exchange.fillOrder`.
+                //  iii.
+                //    For an optimal match, the algorithm must choose either [1005, 502] or [1005, 503] as fill amounts for the right order.
+                //    The algorithm favors the right maker when the exchange rate must be rounded, so the final fill for the right order is [1005, 503].
+                //  iv.
+                //    The right maker fee differs from the right taker fee because their exchange rate differs.
+                //    The right maker always receives the better exchange and fee price.
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1005), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(503), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('47.2718720602069614'), 16), // 47.27%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(497), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber('47.3189087488240827'), 16), // 47.31%
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        const reentrancyTest = (functionNames: string[]) => {
+            _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                const description = `should not allow matchOrders to reenter the Exchange contract via ${functionName}`;
+                it(description, async () => {
+                    const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                        makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                        takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                    });
+                    const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                        makerAddress: makerAddressRight,
+                        takerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                        takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                        feeRecipientAddress: feeRecipientAddressRight,
+                    });
+                    await web3Wrapper.awaitTransactionSuccessAsync(
+                        await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                        constants.AWAIT_TRANSACTION_MINED_MS,
+                    );
+                    await expectTransactionFailedAsync(
+                        exchangeWrapper.matchOrdersAsync(signedOrderLeft, signedOrderRight, takerAddress),
+                        RevertReason.TransferFailed,
+                    );
+                });
+            });
+        };
+        describe('matchOrders reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
+        it('should transfer the correct amounts when orders completely fill each other', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        it('should transfer the correct amounts when orders completely fill each other and taker doesnt take a profit', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(0), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        it('should transfer the correct amounts when left order is completely filled and right order is partially filled', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(20), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 16), // 50%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 16), // 50%
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        it('should transfer the correct amounts when right order is completely filled and left order is partially filled', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 16), // 10%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 16), // 10%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        it('should transfer the correct amounts when consecutive calls are used to completely fill the left order', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             let newERC20BalancesByOwner: ERC20BalancesByOwner;
             let newERC721TokenIdsByOwner: ERC721TokenIdsByOwner;
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 16), // 10%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 16), // 10%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
             // prettier-ignore
             [
                 newERC20BalancesByOwner,
                 // tslint:disable-next-line:trailing-comma
                 newERC721TokenIdsByOwner
-            ] = await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            ] = await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
-            // Verify left order was partially filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
-            // Verify right order was fully filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Construct second right order
             // Note: This order needs makerAssetAmount=90/takerAssetAmount=[anything <= 45] to fully fill the right order.
             //       However, we use 100/50 to ensure a partial fill as we want to go down the "left fill"
             //       branch in the contract twice for this test.
             const signedOrderRight2 = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match signedOrderLeft with signedOrderRight2
             const leftTakerAssetFilledAmount = signedOrderRight.makerAssetAmount;
             const rightTakerAssetFilledAmount = new BigNumber(0);
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts2 = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(45), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 16), // 90% (10% paid earlier)
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(45), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 16), // 90%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(0), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 16), // 90% (10% paid earlier)
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 16), // 90%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight2,
                 takerAddress,
                 newERC20BalancesByOwner,
-                erc721TokenIdsByOwner,
+                newERC721TokenIdsByOwner,
+                expectedTransferAmounts2,
                 leftTakerAssetFilledAmount,
                 rightTakerAssetFilledAmount,
             );
-            // Verify left order was fully filled
-            const leftOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify second right order was partially filled
-            const rightOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight2);
-            expect(rightOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
         });
 
         it('should transfer the correct amounts when consecutive calls are used to completely fill the right order', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
 
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             let newERC20BalancesByOwner: ERC20BalancesByOwner;
             let newERC721TokenIdsByOwner: ERC721TokenIdsByOwner;
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 16), // 4%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(6), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 16), // 4%
+            };
             // prettier-ignore
             [
                 newERC20BalancesByOwner,
                 // tslint:disable-next-line:trailing-comma
                 newERC721TokenIdsByOwner
-            ] = await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            ] = await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
-            // Verify left order was partially filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify right order was fully filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
+
             // Create second left order
             // Note: This order needs makerAssetAmount=96/takerAssetAmount=48 to fully fill the right order.
             //       However, we use 100/50 to ensure a partial fill as we want to go down the "right fill"
             //       branch in the contract twice for this test.
             const signedOrderLeft2 = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(50), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             // Match signedOrderLeft2 with signedOrderRight
             const leftTakerAssetFilledAmount = new BigNumber(0);
@@ -421,198 +766,257 @@ describe('matchOrders', () => {
                 erc20BalancesByOwner[takerAddress][defaultERC20MakerAssetAddress],
             );
             const rightTakerAssetFilledAmount = signedOrderLeft.makerAssetAmount.minus(takerAmountReceived);
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts2 = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(96), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(48), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(96), 16), // 96%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(48), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(96), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(96), 16), // 96%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(0), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(96), 16), // 96%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(96), 16), // 96%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft2,
                 signedOrderRight,
                 takerAddress,
                 newERC20BalancesByOwner,
-                erc721TokenIdsByOwner,
+                newERC721TokenIdsByOwner,
+                expectedTransferAmounts2,
                 leftTakerAssetFilledAmount,
                 rightTakerAssetFilledAmount,
             );
-            // Verify second left order was partially filled
-            const leftOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft2);
-            expect(leftOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
-            // Verify right order was fully filled
-            const rightOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
         it('should transfer the correct amounts if fee recipient is the same across both matched orders', async () => {
             const feeRecipientAddress = feeRecipientAddressLeft;
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 feeRecipientAddress,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
                 feeRecipientAddress,
             });
             // Match orders
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
         });
 
         it('should transfer the correct amounts if taker is also the left order maker', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             takerAddress = signedOrderLeft.makerAddress;
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
         });
 
         it('should transfer the correct amounts if taker is also the right order maker', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             takerAddress = signedOrderRight.makerAddress;
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
         });
 
         it('should transfer the correct amounts if taker is also the left fee recipient', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             takerAddress = feeRecipientAddressLeft;
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
         });
 
         it('should transfer the correct amounts if taker is also the right fee recipient', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             takerAddress = feeRecipientAddressRight;
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
         });
 
         it('should transfer the correct amounts if left maker is the left fee recipient and right maker is the right fee recipient', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: makerAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: makerAddressRight,
             });
             // Match orders
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
         });
 
         it('Should throw if left order is not fillable', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Cancel left order
             await exchangeWrapper.cancelOrderAsync(signedOrderLeft, signedOrderLeft.makerAddress);
@@ -626,18 +1030,12 @@ describe('matchOrders', () => {
         it('Should throw if right order is not fillable', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Cancel right order
             await exchangeWrapper.cancelOrderAsync(signedOrderRight, signedOrderRight.makerAddress);
@@ -651,18 +1049,12 @@ describe('matchOrders', () => {
         it('should throw if there is not a positive spread', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(200), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             return expectTransactionFailedAsync(
@@ -674,18 +1066,13 @@ describe('matchOrders', () => {
         it('should throw if the left maker asset is not equal to the right taker asset ', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             return expectTransactionFailedAsync(
@@ -701,20 +1088,13 @@ describe('matchOrders', () => {
         it('should throw if the right maker asset is not equal to the left taker asset', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
             return expectTransactionFailedAsync(
@@ -727,70 +1107,76 @@ describe('matchOrders', () => {
             // Create orders to match
             const erc721TokenToTransfer = erc721LeftMakerAssetIds[0];
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
                 makerAssetData: assetDataUtils.encodeERC721AssetData(defaultERC721AssetAddress, erc721TokenToTransfer),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 makerAssetAmount: new BigNumber(1),
                 takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC721AssetData(defaultERC721AssetAddress, erc721TokenToTransfer),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: new BigNumber(1),
-                feeRecipientAddress: feeRecipientAddressRight,
             });
             // Match orders
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(0), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 50%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
-            // Verify left order was fully filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify right order was fully filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
         it('should transfer correct amounts when right order maker asset is an ERC721 token', async () => {
             // Create orders to match
             const erc721TokenToTransfer = erc721RightMakerAssetIds[0];
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
-                makerAddress: makerAddressLeft,
-                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC721AssetData(defaultERC721AssetAddress, erc721TokenToTransfer),
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
                 takerAssetAmount: new BigNumber(1),
-                feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
-                makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC721AssetData(defaultERC721AssetAddress, erc721TokenToTransfer),
-                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
                 makerAssetAmount: new BigNumber(1),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
-                feeRecipientAddress: feeRecipientAddressRight,
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(8), 18),
             });
             // Match orders
-            await matchOrderTester.matchOrdersAndVerifyBalancesAsync(
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(8), 18),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
                 signedOrderLeft,
                 signedOrderRight,
                 takerAddress,
                 erc20BalancesByOwner,
                 erc721TokenIdsByOwner,
+                expectedTransferAmounts,
             );
-            // Verify left order was fully filled
-            const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
-            // Verify right order was fully filled
-            const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
     });
 }); // tslint:disable-line:max-file-line-count
diff --git a/packages/contracts/test/exchange/signature_validator.ts b/packages/contracts/test/exchange/signature_validator.ts
index cd4f3d6f3..da2febfd8 100644
--- a/packages/contracts/test/exchange/signature_validator.ts
+++ b/packages/contracts/test/exchange/signature_validator.ts
@@ -9,11 +9,12 @@ import {
     TestSignatureValidatorContract,
     TestSignatureValidatorSignatureValidatorApprovalEventArgs,
 } from '../../generated_contract_wrappers/test_signature_validator';
+import { TestStaticCallReceiverContract } from '../../generated_contract_wrappers/test_static_call_receiver';
 import { ValidatorContract } from '../../generated_contract_wrappers/validator';
 import { WalletContract } from '../../generated_contract_wrappers/wallet';
 import { addressUtils } from '../utils/address_utils';
 import { artifacts } from '../utils/artifacts';
-import { expectContractCallFailed } from '../utils/assertions';
+import { expectContractCallFailed, expectContractCallFailedWithoutReasonAsync } from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
 import { LogDecoder } from '../utils/log_decoder';
@@ -31,6 +32,8 @@ describe('MixinSignatureValidator', () => {
     let signatureValidator: TestSignatureValidatorContract;
     let testWallet: WalletContract;
     let testValidator: ValidatorContract;
+    let maliciousWallet: TestStaticCallReceiverContract;
+    let maliciousValidator: TestStaticCallReceiverContract;
     let signerAddress: string;
     let signerPrivateKey: Buffer;
     let notSignerAddress: string;
@@ -65,6 +68,11 @@ describe('MixinSignatureValidator', () => {
             txDefaults,
             signerAddress,
         );
+        maliciousWallet = maliciousValidator = await TestStaticCallReceiverContract.deployFrom0xArtifactAsync(
+            artifacts.TestStaticCallReceiver,
+            provider,
+            txDefaults,
+        );
         signatureValidatorLogDecoder = new LogDecoder(web3Wrapper);
         await web3Wrapper.awaitTransactionSuccessAsync(
             await signatureValidator.setSignatureValidatorApproval.sendTransactionAsync(testValidator.address, true, {
@@ -72,6 +80,16 @@ describe('MixinSignatureValidator', () => {
             }),
             constants.AWAIT_TRANSACTION_MINED_MS,
         );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await signatureValidator.setSignatureValidatorApproval.sendTransactionAsync(
+                maliciousValidator.address,
+                true,
+                {
+                    from: signerAddress,
+                },
+            ),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
 
         const defaultOrderParams = {
             ...constants.STATIC_ORDER_PARAMS,
@@ -263,32 +281,6 @@ describe('MixinSignatureValidator', () => {
             expect(isValidSignature).to.be.false();
         });
 
-        it('should return true when SignatureType=Caller and signer is caller', async () => {
-            const signature = ethUtil.toBuffer(`0x${SignatureType.Caller}`);
-            const signatureHex = ethUtil.bufferToHex(signature);
-            const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            const isValidSignature = await signatureValidator.publicIsValidSignature.callAsync(
-                orderHashHex,
-                signerAddress,
-                signatureHex,
-                { from: signerAddress },
-            );
-            expect(isValidSignature).to.be.true();
-        });
-
-        it('should return false when SignatureType=Caller and signer is not caller', async () => {
-            const signature = ethUtil.toBuffer(`0x${SignatureType.Caller}`);
-            const signatureHex = ethUtil.bufferToHex(signature);
-            const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            const isValidSignature = await signatureValidator.publicIsValidSignature.callAsync(
-                orderHashHex,
-                signerAddress,
-                signatureHex,
-                { from: notSignerAddress },
-            );
-            expect(isValidSignature).to.be.false();
-        });
-
         it('should return true when SignatureType=Wallet and signature is valid', async () => {
             // Create EIP712 signature
             const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
@@ -334,6 +326,29 @@ describe('MixinSignatureValidator', () => {
             expect(isValidSignature).to.be.false();
         });
 
+        it('should revert when `isValidSignature` attempts to update state and SignatureType=Wallet', async () => {
+            // Create EIP712 signature
+            const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
+            const orderHashBuffer = ethUtil.toBuffer(orderHashHex);
+            const ecSignature = ethUtil.ecsign(orderHashBuffer, signerPrivateKey);
+            // Create 0x signature from EIP712 signature
+            const signature = Buffer.concat([
+                ethUtil.toBuffer(ecSignature.v),
+                ecSignature.r,
+                ecSignature.s,
+                ethUtil.toBuffer(`0x${SignatureType.Wallet}`),
+            ]);
+            const signatureHex = ethUtil.bufferToHex(signature);
+            await expectContractCallFailed(
+                signatureValidator.publicIsValidSignature.callAsync(
+                    orderHashHex,
+                    maliciousWallet.address,
+                    signatureHex,
+                ),
+                RevertReason.WalletError,
+            );
+        });
+
         it('should return true when SignatureType=Validator, signature is valid and validator is approved', async () => {
             const validatorAddress = ethUtil.toBuffer(`${testValidator.address}`);
             const signatureType = ethUtil.toBuffer(`0x${SignatureType.Validator}`);
@@ -364,6 +379,17 @@ describe('MixinSignatureValidator', () => {
             expect(isValidSignature).to.be.false();
         });
 
+        it('should revert when `isValidSignature` attempts to update state and SignatureType=Validator', async () => {
+            const validatorAddress = ethUtil.toBuffer(`${maliciousValidator.address}`);
+            const signatureType = ethUtil.toBuffer(`0x${SignatureType.Validator}`);
+            const signature = Buffer.concat([validatorAddress, signatureType]);
+            const signatureHex = ethUtil.bufferToHex(signature);
+            const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
+            await expectContractCallFailed(
+                signatureValidator.publicIsValidSignature.callAsync(orderHashHex, signerAddress, signatureHex),
+                RevertReason.ValidatorError,
+            );
+        });
         it('should return false when SignatureType=Validator, signature is valid and validator is not approved', async () => {
             // Set approval of signature validator to false
             await web3Wrapper.awaitTransactionSuccessAsync(
@@ -388,53 +414,6 @@ describe('MixinSignatureValidator', () => {
             expect(isValidSignature).to.be.false();
         });
 
-        it('should return true when SignatureType=Trezor and signature is valid', async () => {
-            // Create Trezor signature
-            const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            const orderHashWithTrezorPrefixHex = signatureUtils.addSignedMessagePrefix(orderHashHex, SignerType.Trezor);
-            const orderHashWithTrezorPrefixBuffer = ethUtil.toBuffer(orderHashWithTrezorPrefixHex);
-            const ecSignature = ethUtil.ecsign(orderHashWithTrezorPrefixBuffer, signerPrivateKey);
-            // Create 0x signature from Trezor signature
-            const signature = Buffer.concat([
-                ethUtil.toBuffer(ecSignature.v),
-                ecSignature.r,
-                ecSignature.s,
-                ethUtil.toBuffer(`0x${SignatureType.Trezor}`),
-            ]);
-            const signatureHex = ethUtil.bufferToHex(signature);
-            // Validate signature
-            const isValidSignature = await signatureValidator.publicIsValidSignature.callAsync(
-                orderHashHex,
-                signerAddress,
-                signatureHex,
-            );
-            expect(isValidSignature).to.be.true();
-        });
-
-        it('should return false when SignatureType=Trezor and signature is invalid', async () => {
-            // Create Trezor signature
-            const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            const orderHashWithTrezorPrefixHex = signatureUtils.addSignedMessagePrefix(orderHashHex, SignerType.Trezor);
-            const orderHashWithTrezorPrefixBuffer = ethUtil.toBuffer(orderHashWithTrezorPrefixHex);
-            const ecSignature = ethUtil.ecsign(orderHashWithTrezorPrefixBuffer, signerPrivateKey);
-            // Create 0x signature from Trezor signature
-            const signature = Buffer.concat([
-                ethUtil.toBuffer(ecSignature.v),
-                ecSignature.r,
-                ecSignature.s,
-                ethUtil.toBuffer(`0x${SignatureType.Trezor}`),
-            ]);
-            const signatureHex = ethUtil.bufferToHex(signature);
-            // Validate signature.
-            // This will fail because `signerAddress` signed the message, but we're passing in `notSignerAddress`
-            const isValidSignature = await signatureValidator.publicIsValidSignature.callAsync(
-                orderHashHex,
-                notSignerAddress,
-                signatureHex,
-            );
-            expect(isValidSignature).to.be.false();
-        });
-
         it('should return true when SignatureType=Presigned and signer has presigned hash', async () => {
             // Presign hash
             const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
@@ -468,6 +447,42 @@ describe('MixinSignatureValidator', () => {
             );
             expect(isValidSignature).to.be.false();
         });
+
+        it('should return true when message was signed by a Trezor One (firmware version 1.6.2)', async () => {
+            // messageHash translates to 0x2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b
+            const messageHash = ethUtil.bufferToHex(ethUtil.toBuffer('++++++++++++++++++++++++++++++++'));
+            const signer = '0xc28b145f10f0bcf0fc000e778615f8fd73490bad';
+            const v = ethUtil.toBuffer('0x1c');
+            const r = ethUtil.toBuffer('0x7b888b596ccf87f0bacab0dcb483124973f7420f169b4824d7a12534ac1e9832');
+            const s = ethUtil.toBuffer('0x0c8e14f7edc01459e13965f1da56e0c23ed11e2cca932571eee1292178f90424');
+            const trezorSignatureType = ethUtil.toBuffer(`0x${SignatureType.EthSign}`);
+            const signature = Buffer.concat([v, r, s, trezorSignatureType]);
+            const signatureHex = ethUtil.bufferToHex(signature);
+            const isValidSignature = await signatureValidator.publicIsValidSignature.callAsync(
+                messageHash,
+                signer,
+                signatureHex,
+            );
+            expect(isValidSignature).to.be.true();
+        });
+
+        it('should return true when message was signed by a Trezor Model T (firmware version 2.0.7)', async () => {
+            // messageHash translates to 0x2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b
+            const messageHash = ethUtil.bufferToHex(ethUtil.toBuffer('++++++++++++++++++++++++++++++++'));
+            const signer = '0x98ce6d9345e8ffa7d99ee0822272fae9d2c0e895';
+            const v = ethUtil.toBuffer('0x1c');
+            const r = ethUtil.toBuffer('0x423b71062c327f0ec4fe199b8da0f34185e59b4c1cb4cc23df86cac4a601fb3f');
+            const s = ethUtil.toBuffer('0x53810d6591b5348b7ee08ee812c874b0fdfb942c9849d59512c90e295221091f');
+            const trezorSignatureType = ethUtil.toBuffer(`0x${SignatureType.EthSign}`);
+            const signature = Buffer.concat([v, r, s, trezorSignatureType]);
+            const signatureHex = ethUtil.bufferToHex(signature);
+            const isValidSignature = await signatureValidator.publicIsValidSignature.callAsync(
+                messageHash,
+                signer,
+                signatureHex,
+            );
+            expect(isValidSignature).to.be.true();
+        });
     });
 
     describe('setSignatureValidatorApproval', () => {
diff --git a/packages/contracts/test/exchange/wrapper.ts b/packages/contracts/test/exchange/wrapper.ts
index d48441dca..aadb5ab59 100644
--- a/packages/contracts/test/exchange/wrapper.ts
+++ b/packages/contracts/test/exchange/wrapper.ts
@@ -11,6 +11,7 @@ import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dumm
 import { ERC20ProxyContract } from '../../generated_contract_wrappers/erc20_proxy';
 import { ERC721ProxyContract } from '../../generated_contract_wrappers/erc721_proxy';
 import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
+import { ReentrantERC20TokenContract } from '../../generated_contract_wrappers/reentrant_erc20_token';
 import { artifacts } from '../utils/artifacts';
 import { expectTransactionFailedAsync } from '../utils/assertions';
 import { getLatestBlockTimestampAsync, increaseTimeAndMineBlockAsync } from '../utils/block_timestamp';
@@ -40,6 +41,7 @@ describe('Exchange wrappers', () => {
     let exchange: ExchangeContract;
     let erc20Proxy: ERC20ProxyContract;
     let erc721Proxy: ERC721ProxyContract;
+    let reentrantErc20Token: ReentrantERC20TokenContract;
 
     let exchangeWrapper: ExchangeWrapper;
     let erc20Wrapper: ERC20Wrapper;
@@ -104,6 +106,13 @@ describe('Exchange wrappers', () => {
             constants.AWAIT_TRANSACTION_MINED_MS,
         );
 
+        reentrantErc20Token = await ReentrantERC20TokenContract.deployFrom0xArtifactAsync(
+            artifacts.ReentrantERC20Token,
+            provider,
+            txDefaults,
+            exchange.address,
+        );
+
         defaultMakerAssetAddress = erc20TokenA.address;
         defaultTakerAssetAddress = erc20TokenB.address;
 
@@ -126,6 +135,26 @@ describe('Exchange wrappers', () => {
         await blockchainLifecycle.revertAsync();
     });
     describe('fillOrKillOrder', () => {
+        const reentrancyTest = (functionNames: string[]) => {
+            _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                const description = `should not allow fillOrKillOrder to reenter the Exchange contract via ${functionName}`;
+                it(description, async () => {
+                    const signedOrder = await orderFactory.newSignedOrderAsync({
+                        makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                    });
+                    await web3Wrapper.awaitTransactionSuccessAsync(
+                        await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                        constants.AWAIT_TRANSACTION_MINED_MS,
+                    );
+                    await expectTransactionFailedAsync(
+                        exchangeWrapper.fillOrKillOrderAsync(signedOrder, takerAddress),
+                        RevertReason.TransferFailed,
+                    );
+                });
+            });
+        };
+        describe('fillOrKillOrder reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
         it('should transfer the correct amounts', async () => {
             const signedOrder = await orderFactory.newSignedOrderAsync({
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
@@ -197,6 +226,25 @@ describe('Exchange wrappers', () => {
     });
 
     describe('fillOrderNoThrow', () => {
+        const reentrancyTest = (functionNames: string[]) => {
+            _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                const description = `should not allow fillOrderNoThrow to reenter the Exchange contract via ${functionName}`;
+                it(description, async () => {
+                    const signedOrder = await orderFactory.newSignedOrderAsync({
+                        makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                    });
+                    await web3Wrapper.awaitTransactionSuccessAsync(
+                        await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                        constants.AWAIT_TRANSACTION_MINED_MS,
+                    );
+                    await exchangeWrapper.fillOrderNoThrowAsync(signedOrder, takerAddress);
+                    const newBalances = await erc20Wrapper.getBalancesAsync();
+                    expect(erc20Balances).to.deep.equal(newBalances);
+                });
+            });
+        };
+        describe('fillOrderNoThrow reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
         it('should transfer the correct amounts', async () => {
             const signedOrder = await orderFactory.newSignedOrderAsync({
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
@@ -397,6 +445,26 @@ describe('Exchange wrappers', () => {
         });
 
         describe('batchFillOrders', () => {
+            const reentrancyTest = (functionNames: string[]) => {
+                _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                    const description = `should not allow batchFillOrders to reenter the Exchange contract via ${functionName}`;
+                    it(description, async () => {
+                        const signedOrder = await orderFactory.newSignedOrderAsync({
+                            makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        });
+                        await web3Wrapper.awaitTransactionSuccessAsync(
+                            await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                            constants.AWAIT_TRANSACTION_MINED_MS,
+                        );
+                        await expectTransactionFailedAsync(
+                            exchangeWrapper.batchFillOrdersAsync([signedOrder], takerAddress),
+                            RevertReason.TransferFailed,
+                        );
+                    });
+                });
+            };
+            describe('batchFillOrders reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
             it('should transfer the correct amounts', async () => {
                 const takerAssetFillAmounts: BigNumber[] = [];
                 const makerAssetAddress = erc20TokenA.address;
@@ -446,6 +514,26 @@ describe('Exchange wrappers', () => {
         });
 
         describe('batchFillOrKillOrders', () => {
+            const reentrancyTest = (functionNames: string[]) => {
+                _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                    const description = `should not allow batchFillOrKillOrders to reenter the Exchange contract via ${functionName}`;
+                    it(description, async () => {
+                        const signedOrder = await orderFactory.newSignedOrderAsync({
+                            makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        });
+                        await web3Wrapper.awaitTransactionSuccessAsync(
+                            await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                            constants.AWAIT_TRANSACTION_MINED_MS,
+                        );
+                        await expectTransactionFailedAsync(
+                            exchangeWrapper.batchFillOrKillOrdersAsync([signedOrder], takerAddress),
+                            RevertReason.TransferFailed,
+                        );
+                    });
+                });
+            };
+            describe('batchFillOrKillOrders reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
             it('should transfer the correct amounts', async () => {
                 const takerAssetFillAmounts: BigNumber[] = [];
                 const makerAssetAddress = erc20TokenA.address;
@@ -512,6 +600,25 @@ describe('Exchange wrappers', () => {
         });
 
         describe('batchFillOrdersNoThrow', async () => {
+            const reentrancyTest = (functionNames: string[]) => {
+                _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                    const description = `should not allow batchFillOrdersNoThrow to reenter the Exchange contract via ${functionName}`;
+                    it(description, async () => {
+                        const signedOrder = await orderFactory.newSignedOrderAsync({
+                            makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        });
+                        await web3Wrapper.awaitTransactionSuccessAsync(
+                            await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                            constants.AWAIT_TRANSACTION_MINED_MS,
+                        );
+                        await exchangeWrapper.batchFillOrdersNoThrowAsync([signedOrder], takerAddress);
+                        const newBalances = await erc20Wrapper.getBalancesAsync();
+                        expect(erc20Balances).to.deep.equal(newBalances);
+                    });
+                });
+            };
+            describe('batchFillOrdersNoThrow reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
             it('should transfer the correct amounts', async () => {
                 const takerAssetFillAmounts: BigNumber[] = [];
                 const makerAssetAddress = erc20TokenA.address;
@@ -625,6 +732,28 @@ describe('Exchange wrappers', () => {
         });
 
         describe('marketSellOrders', () => {
+            const reentrancyTest = (functionNames: string[]) => {
+                _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                    const description = `should not allow marketSellOrders to reenter the Exchange contract via ${functionName}`;
+                    it(description, async () => {
+                        const signedOrder = await orderFactory.newSignedOrderAsync({
+                            makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        });
+                        await web3Wrapper.awaitTransactionSuccessAsync(
+                            await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                            constants.AWAIT_TRANSACTION_MINED_MS,
+                        );
+                        await expectTransactionFailedAsync(
+                            exchangeWrapper.marketSellOrdersAsync([signedOrder], takerAddress, {
+                                takerAssetFillAmount: signedOrder.takerAssetAmount,
+                            }),
+                            RevertReason.TransferFailed,
+                        );
+                    });
+                });
+            };
+            describe('marketSellOrders reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
             it('should stop when the entire takerAssetFillAmount is filled', async () => {
                 const takerAssetFillAmount = signedOrders[0].takerAssetAmount.plus(
                     signedOrders[1].takerAssetAmount.div(2),
@@ -717,6 +846,27 @@ describe('Exchange wrappers', () => {
         });
 
         describe('marketSellOrdersNoThrow', () => {
+            const reentrancyTest = (functionNames: string[]) => {
+                _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                    const description = `should not allow marketSellOrdersNoThrow to reenter the Exchange contract via ${functionName}`;
+                    it(description, async () => {
+                        const signedOrder = await orderFactory.newSignedOrderAsync({
+                            makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        });
+                        await web3Wrapper.awaitTransactionSuccessAsync(
+                            await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                            constants.AWAIT_TRANSACTION_MINED_MS,
+                        );
+                        await exchangeWrapper.marketSellOrdersNoThrowAsync([signedOrder], takerAddress, {
+                            takerAssetFillAmount: signedOrder.takerAssetAmount,
+                        });
+                        const newBalances = await erc20Wrapper.getBalancesAsync();
+                        expect(erc20Balances).to.deep.equal(newBalances);
+                    });
+                });
+            };
+            describe('marketSellOrdersNoThrow reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
             it('should stop when the entire takerAssetFillAmount is filled', async () => {
                 const takerAssetFillAmount = signedOrders[0].takerAssetAmount.plus(
                     signedOrders[1].takerAssetAmount.div(2),
@@ -843,6 +993,28 @@ describe('Exchange wrappers', () => {
         });
 
         describe('marketBuyOrders', () => {
+            const reentrancyTest = (functionNames: string[]) => {
+                _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                    const description = `should not allow marketBuyOrders to reenter the Exchange contract via ${functionName}`;
+                    it(description, async () => {
+                        const signedOrder = await orderFactory.newSignedOrderAsync({
+                            makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        });
+                        await web3Wrapper.awaitTransactionSuccessAsync(
+                            await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                            constants.AWAIT_TRANSACTION_MINED_MS,
+                        );
+                        await expectTransactionFailedAsync(
+                            exchangeWrapper.marketBuyOrdersAsync([signedOrder], takerAddress, {
+                                makerAssetFillAmount: signedOrder.makerAssetAmount,
+                            }),
+                            RevertReason.TransferFailed,
+                        );
+                    });
+                });
+            };
+            describe('marketBuyOrders reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
             it('should stop when the entire makerAssetFillAmount is filled', async () => {
                 const makerAssetFillAmount = signedOrders[0].makerAssetAmount.plus(
                     signedOrders[1].makerAssetAmount.div(2),
@@ -933,6 +1105,27 @@ describe('Exchange wrappers', () => {
         });
 
         describe('marketBuyOrdersNoThrow', () => {
+            const reentrancyTest = (functionNames: string[]) => {
+                _.forEach(functionNames, async (functionName: string, functionId: number) => {
+                    const description = `should not allow marketBuyOrdersNoThrow to reenter the Exchange contract via ${functionName}`;
+                    it(description, async () => {
+                        const signedOrder = await orderFactory.newSignedOrderAsync({
+                            makerAssetData: assetDataUtils.encodeERC20AssetData(reentrantErc20Token.address),
+                        });
+                        await web3Wrapper.awaitTransactionSuccessAsync(
+                            await reentrantErc20Token.setCurrentFunction.sendTransactionAsync(functionId),
+                            constants.AWAIT_TRANSACTION_MINED_MS,
+                        );
+                        await exchangeWrapper.marketBuyOrdersNoThrowAsync([signedOrder], takerAddress, {
+                            makerAssetFillAmount: signedOrder.makerAssetAmount,
+                        });
+                        const newBalances = await erc20Wrapper.getBalancesAsync();
+                        expect(erc20Balances).to.deep.equal(newBalances);
+                    });
+                });
+            };
+            describe('marketBuyOrdersNoThrow reentrancy tests', () => reentrancyTest(constants.FUNCTIONS_WITH_MUTEX));
+
             it('should stop when the entire makerAssetFillAmount is filled', async () => {
                 const makerAssetFillAmount = signedOrders[0].makerAssetAmount.plus(
                     signedOrders[1].makerAssetAmount.div(2),
diff --git a/packages/contracts/test/utils/artifacts.ts b/packages/contracts/test/utils/artifacts.ts
index e8a7585ac..5ddb5cc7f 100644
--- a/packages/contracts/test/utils/artifacts.ts
+++ b/packages/contracts/test/utils/artifacts.ts
@@ -16,6 +16,7 @@ import * as MixinAuthorizable from '../../artifacts/MixinAuthorizable.json';
 import * as MultiSigWallet from '../../artifacts/MultiSigWallet.json';
 import * as MultiSigWalletWithTimeLock from '../../artifacts/MultiSigWalletWithTimeLock.json';
 import * as OrderValidator from '../../artifacts/OrderValidator.json';
+import * as ReentrantERC20Token from '../../artifacts/ReentrantERC20Token.json';
 import * as TestAssetProxyDispatcher from '../../artifacts/TestAssetProxyDispatcher.json';
 import * as TestAssetProxyOwner from '../../artifacts/TestAssetProxyOwner.json';
 import * as TestConstants from '../../artifacts/TestConstants.json';
@@ -23,6 +24,7 @@ import * as TestExchangeInternals from '../../artifacts/TestExchangeInternals.js
 import * as TestLibBytes from '../../artifacts/TestLibBytes.json';
 import * as TestLibs from '../../artifacts/TestLibs.json';
 import * as TestSignatureValidator from '../../artifacts/TestSignatureValidator.json';
+import * as TestStaticCallReceiver from '../../artifacts/TestStaticCallReceiver.json';
 import * as TokenRegistry from '../../artifacts/TokenRegistry.json';
 import * as Validator from '../../artifacts/Validator.json';
 import * as Wallet from '../../artifacts/Wallet.json';
@@ -48,6 +50,7 @@ export const artifacts = {
     MultiSigWallet: (MultiSigWallet as any) as ContractArtifact,
     MultiSigWalletWithTimeLock: (MultiSigWalletWithTimeLock as any) as ContractArtifact,
     OrderValidator: (OrderValidator as any) as ContractArtifact,
+    ReentrantERC20Token: (ReentrantERC20Token as any) as ContractArtifact,
     TestAssetProxyOwner: (TestAssetProxyOwner as any) as ContractArtifact,
     TestAssetProxyDispatcher: (TestAssetProxyDispatcher as any) as ContractArtifact,
     TestConstants: (TestConstants as any) as ContractArtifact,
@@ -55,6 +58,7 @@ export const artifacts = {
     TestLibs: (TestLibs as any) as ContractArtifact,
     TestExchangeInternals: (TestExchangeInternals as any) as ContractArtifact,
     TestSignatureValidator: (TestSignatureValidator as any) as ContractArtifact,
+    TestStaticCallReceiver: (TestStaticCallReceiver as any) as ContractArtifact,
     Validator: (Validator as any) as ContractArtifact,
     Wallet: (Wallet as any) as ContractArtifact,
     TokenRegistry: (TokenRegistry as any) as ContractArtifact,
diff --git a/packages/contracts/test/utils/constants.ts b/packages/contracts/test/utils/constants.ts
index 65eaee398..ee4378d2e 100644
--- a/packages/contracts/test/utils/constants.ts
+++ b/packages/contracts/test/utils/constants.ts
@@ -51,4 +51,16 @@ export const constants = {
     WORD_LENGTH: 32,
     ZERO_AMOUNT: new BigNumber(0),
     PERCENTAGE_DENOMINATOR: new BigNumber(10).pow(18),
+    FUNCTIONS_WITH_MUTEX: [
+        'FILL_ORDER',
+        'FILL_OR_KILL_ORDER',
+        'BATCH_FILL_ORDERS',
+        'BATCH_FILL_OR_KILL_ORDERS',
+        'MARKET_BUY_ORDERS',
+        'MARKET_SELL_ORDERS',
+        'MATCH_ORDERS',
+        'CANCEL_ORDER',
+        'CANCEL_ORDERS_UP_TO',
+        'SET_SIGNATURE_VALIDATOR_APPROVAL',
+    ],
 };
diff --git a/packages/contracts/test/utils/fill_order_combinatorial_utils.ts b/packages/contracts/test/utils/fill_order_combinatorial_utils.ts
index a9318571c..92d0f4003 100644
--- a/packages/contracts/test/utils/fill_order_combinatorial_utils.ts
+++ b/packages/contracts/test/utils/fill_order_combinatorial_utils.ts
@@ -467,17 +467,17 @@ export class FillOrderCombinatorialUtils {
             ? remainingTakerAmountToFill
             : alreadyFilledTakerAmount.add(takerAssetFillAmount);
 
-        const expFilledMakerAmount = orderUtils.getPartialAmount(
+        const expFilledMakerAmount = orderUtils.getPartialAmountFloor(
             expFilledTakerAmount,
             signedOrder.takerAssetAmount,
             signedOrder.makerAssetAmount,
         );
-        const expMakerFeePaid = orderUtils.getPartialAmount(
+        const expMakerFeePaid = orderUtils.getPartialAmountFloor(
             expFilledTakerAmount,
             signedOrder.takerAssetAmount,
             signedOrder.makerFee,
         );
-        const expTakerFeePaid = orderUtils.getPartialAmount(
+        const expTakerFeePaid = orderUtils.getPartialAmountFloor(
             expFilledTakerAmount,
             signedOrder.takerAssetAmount,
             signedOrder.takerFee,
@@ -668,7 +668,7 @@ export class FillOrderCombinatorialUtils {
         signedOrder: SignedOrder,
         takerAssetFillAmount: BigNumber,
     ): Promise<void> {
-        const makerAssetFillAmount = orderUtils.getPartialAmount(
+        const makerAssetFillAmount = orderUtils.getPartialAmountFloor(
             takerAssetFillAmount,
             signedOrder.takerAssetAmount,
             signedOrder.makerAssetAmount,
@@ -705,7 +705,7 @@ export class FillOrderCombinatorialUtils {
                 );
         }
 
-        const makerFee = orderUtils.getPartialAmount(
+        const makerFee = orderUtils.getPartialAmountFloor(
             takerAssetFillAmount,
             signedOrder.takerAssetAmount,
             signedOrder.makerFee,
@@ -829,7 +829,7 @@ export class FillOrderCombinatorialUtils {
                 );
         }
 
-        const takerFee = orderUtils.getPartialAmount(
+        const takerFee = orderUtils.getPartialAmountFloor(
             takerAssetFillAmount,
             signedOrder.takerAssetAmount,
             signedOrder.takerFee,
diff --git a/packages/contracts/test/utils/match_order_tester.ts b/packages/contracts/test/utils/match_order_tester.ts
index fa2eabc12..e0c55b834 100644
--- a/packages/contracts/test/utils/match_order_tester.ts
+++ b/packages/contracts/test/utils/match_order_tester.ts
@@ -4,11 +4,20 @@ import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 import * as _ from 'lodash';
 
+import { TransactionReceiptWithDecodedLogs } from '../../../../node_modules/ethereum-types';
+
 import { chaiSetup } from './chai_setup';
 import { ERC20Wrapper } from './erc20_wrapper';
 import { ERC721Wrapper } from './erc721_wrapper';
 import { ExchangeWrapper } from './exchange_wrapper';
-import { ERC20BalancesByOwner, ERC721TokenIdsByOwner, TransferAmountsByMatchOrders as TransferAmounts } from './types';
+import {
+    ERC20BalancesByOwner,
+    ERC721TokenIdsByOwner,
+    OrderInfo,
+    OrderStatus,
+    TransferAmountsByMatchOrders as TransferAmounts,
+    TransferAmountsLoggedByMatchOrders as LoggedTransferAmounts,
+} from './types';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -18,43 +27,107 @@ export class MatchOrderTester {
     private readonly _erc20Wrapper: ERC20Wrapper;
     private readonly _erc721Wrapper: ERC721Wrapper;
     private readonly _feeTokenAddress: string;
-
-    /// @dev Compares a pair of ERC20 balances and a pair of ERC721 token owners.
-    /// @param expectedNewERC20BalancesByOwner Expected ERC20 balances.
-    /// @param realERC20BalancesByOwner Actual ERC20 balances.
-    /// @param expectedNewERC721TokenIdsByOwner Expected ERC721 token owners.
-    /// @param realERC721TokenIdsByOwner Actual ERC20 token owners.
-    /// @return True only if ERC20 balances match and ERC721 token owners match.
-    private static _compareExpectedAndRealBalances(
-        expectedNewERC20BalancesByOwner: ERC20BalancesByOwner,
+    /// @dev Checks values from the logs produced by Exchange.matchOrders against the expected transfer amounts.
+    ///      Values include the amounts transferred from the left/right makers and taker, along with
+    ///      the fees paid on each matched order. These are also the return values of MatchOrders.
+    /// @param signedOrderLeft First matched order.
+    /// @param signedOrderRight Second matched order.
+    /// @param transactionReceipt Transaction receipt and logs produced by Exchange.matchOrders.
+    /// @param takerAddress Address of taker (account that called Exchange.matchOrders)
+    /// @param expectedTransferAmounts Expected amounts transferred as a result of order matching.
+    private static async _assertLogsAsync(
+        signedOrderLeft: SignedOrder,
+        signedOrderRight: SignedOrder,
+        transactionReceipt: TransactionReceiptWithDecodedLogs,
+        takerAddress: string,
+        expectedTransferAmounts: TransferAmounts,
+    ): Promise<void> {
+        // Should have two fill event logs -- one for each order.
+        const transactionFillLogs = _.filter(transactionReceipt.logs, ['event', 'Fill']);
+        expect(transactionFillLogs.length, 'Checking number of logs').to.be.equal(2);
+        // First log is for left fill
+        const leftLog = (transactionFillLogs[0] as any).args as LoggedTransferAmounts;
+        expect(leftLog.makerAddress, 'Checking logged maker address of left order').to.be.equal(
+            signedOrderLeft.makerAddress,
+        );
+        expect(leftLog.takerAddress, 'Checking logged taker address of right order').to.be.equal(takerAddress);
+        const amountBoughtByLeftMaker = new BigNumber(leftLog.takerAssetFilledAmount);
+        const amountSoldByLeftMaker = new BigNumber(leftLog.makerAssetFilledAmount);
+        const feePaidByLeftMaker = new BigNumber(leftLog.makerFeePaid);
+        const feePaidByTakerLeft = new BigNumber(leftLog.takerFeePaid);
+        // Second log is for right fill
+        const rightLog = (transactionFillLogs[1] as any).args as LoggedTransferAmounts;
+        expect(rightLog.makerAddress, 'Checking logged maker address of right order').to.be.equal(
+            signedOrderRight.makerAddress,
+        );
+        expect(rightLog.takerAddress, 'Checking loggerd taker address of right order').to.be.equal(takerAddress);
+        const amountBoughtByRightMaker = new BigNumber(rightLog.takerAssetFilledAmount);
+        const amountSoldByRightMaker = new BigNumber(rightLog.makerAssetFilledAmount);
+        const feePaidByRightMaker = new BigNumber(rightLog.makerFeePaid);
+        const feePaidByTakerRight = new BigNumber(rightLog.takerFeePaid);
+        // Derive amount received by taker
+        const amountReceivedByTaker = amountSoldByLeftMaker.sub(amountBoughtByRightMaker);
+        // Assert log values - left order
+        expect(amountBoughtByLeftMaker, 'Checking logged amount bought by left maker').to.be.bignumber.equal(
+            expectedTransferAmounts.amountBoughtByLeftMaker,
+        );
+        expect(amountSoldByLeftMaker, 'Checking logged amount sold by left maker').to.be.bignumber.equal(
+            expectedTransferAmounts.amountSoldByLeftMaker,
+        );
+        expect(feePaidByLeftMaker, 'Checking logged fee paid by left maker').to.be.bignumber.equal(
+            expectedTransferAmounts.feePaidByLeftMaker,
+        );
+        expect(feePaidByTakerLeft, 'Checking logged fee paid on left order by taker').to.be.bignumber.equal(
+            expectedTransferAmounts.feePaidByTakerLeft,
+        );
+        // Assert log values - right order
+        expect(amountBoughtByRightMaker, 'Checking logged amount bought by right maker').to.be.bignumber.equal(
+            expectedTransferAmounts.amountBoughtByRightMaker,
+        );
+        expect(amountSoldByRightMaker, 'Checking logged amount sold by right maker').to.be.bignumber.equal(
+            expectedTransferAmounts.amountSoldByRightMaker,
+        );
+        expect(feePaidByRightMaker, 'Checking logged fee paid by right maker').to.be.bignumber.equal(
+            expectedTransferAmounts.feePaidByRightMaker,
+        );
+        expect(feePaidByTakerRight, 'Checking logged fee paid on right order by taker').to.be.bignumber.equal(
+            expectedTransferAmounts.feePaidByTakerRight,
+        );
+        // Assert derived amount received by taker
+        expect(amountReceivedByTaker, 'Checking logged amount received by taker').to.be.bignumber.equal(
+            expectedTransferAmounts.amountReceivedByTaker,
+        );
+    }
+    /// @dev Asserts all expected ERC20 and ERC721 account holdings match the real holdings.
+    /// @param expectedERC20BalancesByOwner Expected ERC20 balances.
+    /// @param realERC20BalancesByOwner Real ERC20 balances.
+    /// @param expectedERC721TokenIdsByOwner Expected ERC721 token owners.
+    /// @param realERC721TokenIdsByOwner Real ERC20 token owners.
+    private static async _assertAllKnownBalancesAsync(
+        expectedERC20BalancesByOwner: ERC20BalancesByOwner,
         realERC20BalancesByOwner: ERC20BalancesByOwner,
-        expectedNewERC721TokenIdsByOwner: ERC721TokenIdsByOwner,
+        expectedERC721TokenIdsByOwner: ERC721TokenIdsByOwner,
         realERC721TokenIdsByOwner: ERC721TokenIdsByOwner,
-    ): boolean {
+    ): Promise<void> {
         // ERC20 Balances
-        const doesErc20BalancesMatch = _.isEqual(expectedNewERC20BalancesByOwner, realERC20BalancesByOwner);
-        if (!doesErc20BalancesMatch) {
-            return false;
-        }
+        const areERC20BalancesEqual = _.isEqual(expectedERC20BalancesByOwner, realERC20BalancesByOwner);
+        expect(areERC20BalancesEqual, 'Checking all known ERC20 account balances').to.be.true();
         // ERC721 Token Ids
-        const sortedExpectedNewERC721TokenIdsByOwner = _.mapValues(
-            expectedNewERC721TokenIdsByOwner,
-            tokenIdsByOwner => {
-                _.mapValues(tokenIdsByOwner, tokenIds => {
-                    _.sortBy(tokenIds);
-                });
-            },
-        );
+        const sortedExpectedNewERC721TokenIdsByOwner = _.mapValues(expectedERC721TokenIdsByOwner, tokenIdsByOwner => {
+            _.mapValues(tokenIdsByOwner, tokenIds => {
+                _.sortBy(tokenIds);
+            });
+        });
         const sortedNewERC721TokenIdsByOwner = _.mapValues(realERC721TokenIdsByOwner, tokenIdsByOwner => {
             _.mapValues(tokenIdsByOwner, tokenIds => {
                 _.sortBy(tokenIds);
             });
         });
-        const doesErc721TokenIdsMatch = _.isEqual(
+        const areERC721TokenIdsEqual = _.isEqual(
             sortedExpectedNewERC721TokenIdsByOwner,
             sortedNewERC721TokenIdsByOwner,
         );
-        return doesErc721TokenIdsMatch;
+        expect(areERC721TokenIdsEqual, 'Checking all known ERC721 account balances').to.be.true();
     }
     /// @dev Constructs new MatchOrderTester.
     /// @param exchangeWrapper Used to call to the Exchange.
@@ -72,150 +145,199 @@ export class MatchOrderTester {
         this._erc721Wrapper = erc721Wrapper;
         this._feeTokenAddress = feeTokenAddress;
     }
-    /// @dev Matches two complementary orders and validates results.
-    ///      Validation either succeeds or throws.
+    /// @dev Matches two complementary orders and asserts results.
     /// @param signedOrderLeft First matched order.
     /// @param signedOrderRight Second matched order.
     /// @param takerAddress Address of taker (the address who matched the two orders)
     /// @param erc20BalancesByOwner Current ERC20 balances.
     /// @param erc721TokenIdsByOwner Current ERC721 token owners.
-    /// @param initialTakerAssetFilledAmountLeft Current amount the left order has been filled.
-    /// @param initialTakerAssetFilledAmountRight Current amount the right order has been filled.
+    /// @param expectedTransferAmounts Expected amounts transferred as a result of order matching.
+    /// @param initialLeftOrderFilledAmount How much left order has been filled, prior to matching orders.
+    /// @param initialRightOrderFilledAmount How much the right order has been filled, prior to matching orders.
     /// @return New ERC20 balances & ERC721 token owners.
-    public async matchOrdersAndVerifyBalancesAsync(
+    public async matchOrdersAndAssertEffectsAsync(
         signedOrderLeft: SignedOrder,
         signedOrderRight: SignedOrder,
         takerAddress: string,
         erc20BalancesByOwner: ERC20BalancesByOwner,
         erc721TokenIdsByOwner: ERC721TokenIdsByOwner,
-        initialTakerAssetFilledAmountLeft?: BigNumber,
-        initialTakerAssetFilledAmountRight?: BigNumber,
+        expectedTransferAmounts: TransferAmounts,
+        initialLeftOrderFilledAmount: BigNumber = new BigNumber(0),
+        initialRightOrderFilledAmount: BigNumber = new BigNumber(0),
     ): Promise<[ERC20BalancesByOwner, ERC721TokenIdsByOwner]> {
-        // Verify Left order preconditions
-        const orderTakerAssetFilledAmountLeft = await this._exchangeWrapper.getTakerAssetFilledAmountAsync(
-            orderHashUtils.getOrderHashHex(signedOrderLeft),
-        );
-        const expectedOrderFilledAmountLeft = initialTakerAssetFilledAmountLeft
-            ? initialTakerAssetFilledAmountLeft
-            : new BigNumber(0);
-        expect(expectedOrderFilledAmountLeft).to.be.bignumber.equal(orderTakerAssetFilledAmountLeft);
-        // Verify Right order preconditions
-        const orderTakerAssetFilledAmountRight = await this._exchangeWrapper.getTakerAssetFilledAmountAsync(
-            orderHashUtils.getOrderHashHex(signedOrderRight),
+        // Assert initial order states
+        await this._assertInitialOrderStatesAsync(
+            signedOrderLeft,
+            signedOrderRight,
+            initialLeftOrderFilledAmount,
+            initialRightOrderFilledAmount,
         );
-        const expectedOrderFilledAmountRight = initialTakerAssetFilledAmountRight
-            ? initialTakerAssetFilledAmountRight
-            : new BigNumber(0);
-        expect(expectedOrderFilledAmountRight).to.be.bignumber.equal(orderTakerAssetFilledAmountRight);
         // Match left & right orders
-        await this._exchangeWrapper.matchOrdersAsync(signedOrderLeft, signedOrderRight, takerAddress);
+        const transactionReceipt = await this._exchangeWrapper.matchOrdersAsync(
+            signedOrderLeft,
+            signedOrderRight,
+            takerAddress,
+        );
         const newERC20BalancesByOwner = await this._erc20Wrapper.getBalancesAsync();
         const newERC721TokenIdsByOwner = await this._erc721Wrapper.getBalancesAsync();
-        // Calculate expected balance changes
-        const expectedTransferAmounts = await this._calculateExpectedTransferAmountsAsync(
+        // Assert logs
+        await MatchOrderTester._assertLogsAsync(
             signedOrderLeft,
             signedOrderRight,
-            orderTakerAssetFilledAmountLeft,
-            orderTakerAssetFilledAmountRight,
+            transactionReceipt,
+            takerAddress,
+            expectedTransferAmounts,
         );
-        let expectedERC20BalancesByOwner: ERC20BalancesByOwner;
-        let expectedERC721TokenIdsByOwner: ERC721TokenIdsByOwner;
-        [expectedERC20BalancesByOwner, expectedERC721TokenIdsByOwner] = this._calculateExpectedBalances(
+        // Assert exchange state
+        await this._assertExchangeStateAsync(
             signedOrderLeft,
             signedOrderRight,
-            takerAddress,
-            erc20BalancesByOwner,
-            erc721TokenIdsByOwner,
+            initialLeftOrderFilledAmount,
+            initialRightOrderFilledAmount,
             expectedTransferAmounts,
         );
-        // Assert our expected balances are equal to the actual balances
-        const didExpectedBalancesMatchRealBalances = MatchOrderTester._compareExpectedAndRealBalances(
-            expectedERC20BalancesByOwner,
+        // Assert balances of makers, taker, and fee recipients
+        await this._assertBalancesAsync(
+            signedOrderLeft,
+            signedOrderRight,
+            erc20BalancesByOwner,
+            erc721TokenIdsByOwner,
             newERC20BalancesByOwner,
-            expectedERC721TokenIdsByOwner,
             newERC721TokenIdsByOwner,
+            expectedTransferAmounts,
+            takerAddress,
         );
-        expect(didExpectedBalancesMatchRealBalances).to.be.true();
         return [newERC20BalancesByOwner, newERC721TokenIdsByOwner];
     }
-    /// @dev Calculates expected transfer amounts between order makers, fee recipients, and
-    ///      the taker when two orders are matched.
+    /// @dev Asserts initial exchange state for the left and right orders.
+    /// @param signedOrderLeft First matched order.
+    /// @param signedOrderRight Second matched order.
+    /// @param expectedOrderFilledAmountLeft How much left order has been filled, prior to matching orders.
+    /// @param expectedOrderFilledAmountRight How much the right order has been filled, prior to matching orders.
+    private async _assertInitialOrderStatesAsync(
+        signedOrderLeft: SignedOrder,
+        signedOrderRight: SignedOrder,
+        expectedOrderFilledAmountLeft: BigNumber,
+        expectedOrderFilledAmountRight: BigNumber,
+    ): Promise<void> {
+        // Assert left order initial state
+        const orderTakerAssetFilledAmountLeft = await this._exchangeWrapper.getTakerAssetFilledAmountAsync(
+            orderHashUtils.getOrderHashHex(signedOrderLeft),
+        );
+        expect(orderTakerAssetFilledAmountLeft, 'Checking inital state of left order').to.be.bignumber.equal(
+            expectedOrderFilledAmountLeft,
+        );
+        // Assert right order initial state
+        const orderTakerAssetFilledAmountRight = await this._exchangeWrapper.getTakerAssetFilledAmountAsync(
+            orderHashUtils.getOrderHashHex(signedOrderRight),
+        );
+        expect(orderTakerAssetFilledAmountRight, 'Checking inital state of right order').to.be.bignumber.equal(
+            expectedOrderFilledAmountRight,
+        );
+    }
+    /// @dev Asserts the exchange state against the expected amounts transferred by from matching orders.
     /// @param signedOrderLeft First matched order.
     /// @param signedOrderRight Second matched order.
-    /// @param orderTakerAssetFilledAmountLeft How much left order has been filled, prior to matching orders.
-    /// @param orderTakerAssetFilledAmountRight How much the right order has been filled, prior to matching orders.
+    /// @param initialLeftOrderFilledAmount How much left order has been filled, prior to matching orders.
+    /// @param initialRightOrderFilledAmount How much the right order has been filled, prior to matching orders.
     /// @return TransferAmounts A struct containing the expected transfer amounts.
-    private async _calculateExpectedTransferAmountsAsync(
+    private async _assertExchangeStateAsync(
         signedOrderLeft: SignedOrder,
         signedOrderRight: SignedOrder,
-        orderTakerAssetFilledAmountLeft: BigNumber,
-        orderTakerAssetFilledAmountRight: BigNumber,
-    ): Promise<TransferAmounts> {
+        initialLeftOrderFilledAmount: BigNumber,
+        initialRightOrderFilledAmount: BigNumber,
+        expectedTransferAmounts: TransferAmounts,
+    ): Promise<void> {
+        // Assert state for left order: amount bought by left maker
         let amountBoughtByLeftMaker = await this._exchangeWrapper.getTakerAssetFilledAmountAsync(
             orderHashUtils.getOrderHashHex(signedOrderLeft),
         );
-        amountBoughtByLeftMaker = amountBoughtByLeftMaker.minus(orderTakerAssetFilledAmountLeft);
-        const amountSoldByLeftMaker = amountBoughtByLeftMaker
-            .times(signedOrderLeft.makerAssetAmount)
-            .dividedToIntegerBy(signedOrderLeft.takerAssetAmount);
-        const amountReceivedByRightMaker = amountBoughtByLeftMaker
-            .times(signedOrderRight.takerAssetAmount)
-            .dividedToIntegerBy(signedOrderRight.makerAssetAmount);
-        const amountReceivedByTaker = amountSoldByLeftMaker.minus(amountReceivedByRightMaker);
+        amountBoughtByLeftMaker = amountBoughtByLeftMaker.minus(initialLeftOrderFilledAmount);
+        expect(amountBoughtByLeftMaker, 'Checking exchange state for left order').to.be.bignumber.equal(
+            expectedTransferAmounts.amountBoughtByLeftMaker,
+        );
+        // Assert state for right order: amount bought by right maker
         let amountBoughtByRightMaker = await this._exchangeWrapper.getTakerAssetFilledAmountAsync(
             orderHashUtils.getOrderHashHex(signedOrderRight),
         );
-        amountBoughtByRightMaker = amountBoughtByRightMaker.minus(orderTakerAssetFilledAmountRight);
-        const amountSoldByRightMaker = amountBoughtByRightMaker
-            .times(signedOrderRight.makerAssetAmount)
-            .dividedToIntegerBy(signedOrderRight.takerAssetAmount);
-        const amountReceivedByLeftMaker = amountSoldByRightMaker;
-        const feePaidByLeftMaker = signedOrderLeft.makerFee
-            .times(amountSoldByLeftMaker)
-            .dividedToIntegerBy(signedOrderLeft.makerAssetAmount);
-        const feePaidByRightMaker = signedOrderRight.makerFee
-            .times(amountSoldByRightMaker)
-            .dividedToIntegerBy(signedOrderRight.makerAssetAmount);
-        const feePaidByTakerLeft = signedOrderLeft.takerFee
-            .times(amountSoldByLeftMaker)
-            .dividedToIntegerBy(signedOrderLeft.makerAssetAmount);
-        const feePaidByTakerRight = signedOrderRight.takerFee
-            .times(amountSoldByRightMaker)
-            .dividedToIntegerBy(signedOrderRight.makerAssetAmount);
-        const totalFeePaidByTaker = feePaidByTakerLeft.add(feePaidByTakerRight);
-        const feeReceivedLeft = feePaidByLeftMaker.add(feePaidByTakerLeft);
-        const feeReceivedRight = feePaidByRightMaker.add(feePaidByTakerRight);
-        // Return values
-        const expectedTransferAmounts = {
-            // Left Maker
-            amountBoughtByLeftMaker,
-            amountSoldByLeftMaker,
-            amountReceivedByLeftMaker,
-            feePaidByLeftMaker,
-            // Right Maker
-            amountBoughtByRightMaker,
-            amountSoldByRightMaker,
-            amountReceivedByRightMaker,
-            feePaidByRightMaker,
-            // Taker
-            amountReceivedByTaker,
-            feePaidByTakerLeft,
-            feePaidByTakerRight,
-            totalFeePaidByTaker,
-            // Fee Recipients
-            feeReceivedLeft,
-            feeReceivedRight,
-        };
-        return expectedTransferAmounts;
+        amountBoughtByRightMaker = amountBoughtByRightMaker.minus(initialRightOrderFilledAmount);
+        expect(amountBoughtByRightMaker, 'Checking exchange state for right order').to.be.bignumber.equal(
+            expectedTransferAmounts.amountBoughtByRightMaker,
+        );
+        // Assert left order status
+        const maxAmountBoughtByLeftMaker = signedOrderLeft.takerAssetAmount.minus(initialLeftOrderFilledAmount);
+        const leftOrderInfo: OrderInfo = await this._exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
+        const leftExpectedStatus = expectedTransferAmounts.amountBoughtByLeftMaker.equals(maxAmountBoughtByLeftMaker)
+            ? OrderStatus.FULLY_FILLED
+            : OrderStatus.FILLABLE;
+        expect(leftOrderInfo.orderStatus as OrderStatus, 'Checking exchange status for left order').to.be.equal(
+            leftExpectedStatus,
+        );
+        // Assert right order status
+        const maxAmountBoughtByRightMaker = signedOrderRight.takerAssetAmount.minus(initialRightOrderFilledAmount);
+        const rightOrderInfo: OrderInfo = await this._exchangeWrapper.getOrderInfoAsync(signedOrderRight);
+        const rightExpectedStatus = expectedTransferAmounts.amountBoughtByRightMaker.equals(maxAmountBoughtByRightMaker)
+            ? OrderStatus.FULLY_FILLED
+            : OrderStatus.FILLABLE;
+        expect(rightOrderInfo.orderStatus as OrderStatus, 'Checking exchange status for right order').to.be.equal(
+            rightExpectedStatus,
+        );
+    }
+    /// @dev Asserts account balances after matching orders.
+    /// @param signedOrderLeft First matched order.
+    /// @param signedOrderRight Second matched order.
+    /// @param initialERC20BalancesByOwner ERC20 balances prior to order matching.
+    /// @param initialERC721TokenIdsByOwner ERC721 token owners prior to order matching.
+    /// @param finalERC20BalancesByOwner ERC20 balances after order matching.
+    /// @param finalERC721TokenIdsByOwner ERC721 token owners after order matching.
+    /// @param expectedTransferAmounts Expected amounts transferred as a result of order matching.
+    /// @param takerAddress Address of taker (account that called Exchange.matchOrders).
+    private async _assertBalancesAsync(
+        signedOrderLeft: SignedOrder,
+        signedOrderRight: SignedOrder,
+        initialERC20BalancesByOwner: ERC20BalancesByOwner,
+        initialERC721TokenIdsByOwner: ERC721TokenIdsByOwner,
+        finalERC20BalancesByOwner: ERC20BalancesByOwner,
+        finalERC721TokenIdsByOwner: ERC721TokenIdsByOwner,
+        expectedTransferAmounts: TransferAmounts,
+        takerAddress: string,
+    ): Promise<void> {
+        let expectedERC20BalancesByOwner: ERC20BalancesByOwner;
+        let expectedERC721TokenIdsByOwner: ERC721TokenIdsByOwner;
+        [expectedERC20BalancesByOwner, expectedERC721TokenIdsByOwner] = this._calculateExpectedBalances(
+            signedOrderLeft,
+            signedOrderRight,
+            takerAddress,
+            initialERC20BalancesByOwner,
+            initialERC721TokenIdsByOwner,
+            expectedTransferAmounts,
+        );
+        // Assert balances of makers, taker, and fee recipients
+        await this._assertMakerTakerAndFeeRecipientBalancesAsync(
+            signedOrderLeft,
+            signedOrderRight,
+            expectedERC20BalancesByOwner,
+            finalERC20BalancesByOwner,
+            expectedERC721TokenIdsByOwner,
+            finalERC721TokenIdsByOwner,
+            takerAddress,
+        );
+        // Assert balances for all known accounts
+        await MatchOrderTester._assertAllKnownBalancesAsync(
+            expectedERC20BalancesByOwner,
+            finalERC20BalancesByOwner,
+            expectedERC721TokenIdsByOwner,
+            finalERC721TokenIdsByOwner,
+        );
     }
     /// @dev Calculates the expected balances of order makers, fee recipients, and the taker,
     ///      as a result of matching two orders.
-    /// @param signedOrderLeft First matched order.
+    /// @param signedOrderRight First matched order.
     /// @param signedOrderRight Second matched order.
     /// @param takerAddress Address of taker (the address who matched the two orders)
     /// @param erc20BalancesByOwner Current ERC20 balances.
     /// @param erc721TokenIdsByOwner Current ERC721 token owners.
-    /// @param expectedTransferAmounts A struct containing the expected transfer amounts.
+    /// @param expectedTransferAmounts Expected amounts transferred as a result of order matching.
     /// @return Expected ERC20 balances & ERC721 token owners after orders have been matched.
     private _calculateExpectedBalances(
         signedOrderLeft: SignedOrder,
@@ -247,7 +369,7 @@ export class MatchOrderTester {
             expectedNewERC20BalancesByOwner[makerAddressRight][
                 takerAssetAddressRight
             ] = expectedNewERC20BalancesByOwner[makerAddressRight][takerAssetAddressRight].add(
-                expectedTransferAmounts.amountReceivedByRightMaker,
+                expectedTransferAmounts.amountBoughtByRightMaker,
             );
             // Taker
             expectedNewERC20BalancesByOwner[takerAddress][makerAssetAddressLeft] = expectedNewERC20BalancesByOwner[
@@ -277,7 +399,7 @@ export class MatchOrderTester {
             // Left Maker
             expectedNewERC20BalancesByOwner[makerAddressLeft][takerAssetAddressLeft] = expectedNewERC20BalancesByOwner[
                 makerAddressLeft
-            ][takerAssetAddressLeft].add(expectedTransferAmounts.amountReceivedByLeftMaker);
+            ][takerAssetAddressLeft].add(expectedTransferAmounts.amountBoughtByLeftMaker);
             // Right Maker
             expectedNewERC20BalancesByOwner[makerAddressRight][
                 makerAssetAddressRight
@@ -307,20 +429,138 @@ export class MatchOrderTester {
         // Taker Fees
         expectedNewERC20BalancesByOwner[takerAddress][this._feeTokenAddress] = expectedNewERC20BalancesByOwner[
             takerAddress
-        ][this._feeTokenAddress].minus(expectedTransferAmounts.totalFeePaidByTaker);
+        ][this._feeTokenAddress].minus(
+            expectedTransferAmounts.feePaidByTakerLeft.add(expectedTransferAmounts.feePaidByTakerRight),
+        );
         // Left Fee Recipient Fees
         expectedNewERC20BalancesByOwner[feeRecipientAddressLeft][
             this._feeTokenAddress
         ] = expectedNewERC20BalancesByOwner[feeRecipientAddressLeft][this._feeTokenAddress].add(
-            expectedTransferAmounts.feeReceivedLeft,
+            expectedTransferAmounts.feePaidByLeftMaker.add(expectedTransferAmounts.feePaidByTakerLeft),
         );
         // Right Fee Recipient Fees
         expectedNewERC20BalancesByOwner[feeRecipientAddressRight][
             this._feeTokenAddress
         ] = expectedNewERC20BalancesByOwner[feeRecipientAddressRight][this._feeTokenAddress].add(
-            expectedTransferAmounts.feeReceivedRight,
+            expectedTransferAmounts.feePaidByRightMaker.add(expectedTransferAmounts.feePaidByTakerRight),
         );
 
         return [expectedNewERC20BalancesByOwner, expectedNewERC721TokenIdsByOwner];
     }
-}
+    /// @dev Asserts ERC20 account balances and ERC721 token holdings that result from order matching.
+    ///      Specifically checks balances of makers, taker and fee recipients.
+    /// @param signedOrderLeft First matched order.
+    /// @param signedOrderRight Second matched order.
+    /// @param expectedERC20BalancesByOwner Expected ERC20 balances.
+    /// @param realERC20BalancesByOwner Real ERC20 balances.
+    /// @param expectedERC721TokenIdsByOwner Expected ERC721 token owners.
+    /// @param realERC721TokenIdsByOwner Real ERC20 token owners.
+    /// @param takerAddress Address of taker (account that called Exchange.matchOrders).
+    private async _assertMakerTakerAndFeeRecipientBalancesAsync(
+        signedOrderLeft: SignedOrder,
+        signedOrderRight: SignedOrder,
+        expectedERC20BalancesByOwner: ERC20BalancesByOwner,
+        realERC20BalancesByOwner: ERC20BalancesByOwner,
+        expectedERC721TokenIdsByOwner: ERC721TokenIdsByOwner,
+        realERC721TokenIdsByOwner: ERC721TokenIdsByOwner,
+        takerAddress: string,
+    ): Promise<void> {
+        // Individual balance comparisons
+        const makerAssetProxyIdLeft = assetDataUtils.decodeAssetProxyId(signedOrderLeft.makerAssetData);
+        const makerERC20AssetDataLeft =
+            makerAssetProxyIdLeft === AssetProxyId.ERC20
+                ? assetDataUtils.decodeERC20AssetData(signedOrderLeft.makerAssetData)
+                : assetDataUtils.decodeERC721AssetData(signedOrderLeft.makerAssetData);
+        const makerAssetAddressLeft = makerERC20AssetDataLeft.tokenAddress;
+        const makerAssetProxyIdRight = assetDataUtils.decodeAssetProxyId(signedOrderRight.makerAssetData);
+        const makerERC20AssetDataRight =
+            makerAssetProxyIdRight === AssetProxyId.ERC20
+                ? assetDataUtils.decodeERC20AssetData(signedOrderRight.makerAssetData)
+                : assetDataUtils.decodeERC721AssetData(signedOrderRight.makerAssetData);
+        const makerAssetAddressRight = makerERC20AssetDataRight.tokenAddress;
+        if (makerAssetProxyIdLeft === AssetProxyId.ERC20) {
+            expect(
+                realERC20BalancesByOwner[signedOrderLeft.makerAddress][makerAssetAddressLeft],
+                'Checking left maker egress ERC20 account balance',
+            ).to.be.bignumber.equal(expectedERC20BalancesByOwner[signedOrderLeft.makerAddress][makerAssetAddressLeft]);
+            expect(
+                realERC20BalancesByOwner[signedOrderRight.makerAddress][makerAssetAddressLeft],
+                'Checking right maker ingress ERC20 account balance',
+            ).to.be.bignumber.equal(expectedERC20BalancesByOwner[signedOrderRight.makerAddress][makerAssetAddressLeft]);
+            expect(
+                realERC20BalancesByOwner[takerAddress][makerAssetAddressLeft],
+                'Checking taker ingress ERC20 account balance',
+            ).to.be.bignumber.equal(expectedERC20BalancesByOwner[takerAddress][makerAssetAddressLeft]);
+        } else if (makerAssetProxyIdLeft === AssetProxyId.ERC721) {
+            expect(
+                realERC721TokenIdsByOwner[signedOrderLeft.makerAddress][makerAssetAddressLeft].sort(),
+                'Checking left maker egress ERC721 account holdings',
+            ).to.be.deep.equal(
+                expectedERC721TokenIdsByOwner[signedOrderLeft.makerAddress][makerAssetAddressLeft].sort(),
+            );
+            expect(
+                realERC721TokenIdsByOwner[signedOrderRight.makerAddress][makerAssetAddressLeft].sort(),
+                'Checking right maker ERC721 account holdings',
+            ).to.be.deep.equal(
+                expectedERC721TokenIdsByOwner[signedOrderRight.makerAddress][makerAssetAddressLeft].sort(),
+            );
+            expect(
+                realERC721TokenIdsByOwner[takerAddress][makerAssetAddressLeft].sort(),
+                'Checking taker ingress ERC721 account holdings',
+            ).to.be.deep.equal(expectedERC721TokenIdsByOwner[takerAddress][makerAssetAddressLeft].sort());
+        } else {
+            throw new Error(`Unhandled Asset Proxy ID: ${makerAssetProxyIdLeft}`);
+        }
+        if (makerAssetProxyIdRight === AssetProxyId.ERC20) {
+            expect(
+                realERC20BalancesByOwner[signedOrderLeft.makerAddress][makerAssetAddressRight],
+                'Checking left maker ingress ERC20 account balance',
+            ).to.be.bignumber.equal(expectedERC20BalancesByOwner[signedOrderLeft.makerAddress][makerAssetAddressRight]);
+            expect(
+                realERC20BalancesByOwner[signedOrderRight.makerAddress][makerAssetAddressRight],
+                'Checking right maker egress ERC20 account balance',
+            ).to.be.bignumber.equal(
+                expectedERC20BalancesByOwner[signedOrderRight.makerAddress][makerAssetAddressRight],
+            );
+        } else if (makerAssetProxyIdRight === AssetProxyId.ERC721) {
+            expect(
+                realERC721TokenIdsByOwner[signedOrderLeft.makerAddress][makerAssetAddressRight].sort(),
+                'Checking left maker ingress ERC721 account holdings',
+            ).to.be.deep.equal(
+                expectedERC721TokenIdsByOwner[signedOrderLeft.makerAddress][makerAssetAddressRight].sort(),
+            );
+            expect(
+                realERC721TokenIdsByOwner[signedOrderRight.makerAddress][makerAssetAddressRight],
+                'Checking right maker agress ERC721 account holdings',
+            ).to.be.deep.equal(expectedERC721TokenIdsByOwner[signedOrderRight.makerAddress][makerAssetAddressRight]);
+        } else {
+            throw new Error(`Unhandled Asset Proxy ID: ${makerAssetProxyIdRight}`);
+        }
+        // Paid fees
+        expect(
+            realERC20BalancesByOwner[signedOrderLeft.makerAddress][this._feeTokenAddress],
+            'Checking left maker egress ERC20 account fees',
+        ).to.be.bignumber.equal(expectedERC20BalancesByOwner[signedOrderLeft.makerAddress][this._feeTokenAddress]);
+        expect(
+            realERC20BalancesByOwner[signedOrderRight.makerAddress][this._feeTokenAddress],
+            'Checking right maker egress ERC20 account fees',
+        ).to.be.bignumber.equal(expectedERC20BalancesByOwner[signedOrderRight.makerAddress][this._feeTokenAddress]);
+        expect(
+            realERC20BalancesByOwner[takerAddress][this._feeTokenAddress],
+            'Checking taker egress ERC20 account fees',
+        ).to.be.bignumber.equal(expectedERC20BalancesByOwner[takerAddress][this._feeTokenAddress]);
+        // Received fees
+        expect(
+            realERC20BalancesByOwner[signedOrderLeft.feeRecipientAddress][this._feeTokenAddress],
+            'Checking left fee recipient ingress ERC20 account fees',
+        ).to.be.bignumber.equal(
+            expectedERC20BalancesByOwner[signedOrderLeft.feeRecipientAddress][this._feeTokenAddress],
+        );
+        expect(
+            realERC20BalancesByOwner[signedOrderRight.feeRecipientAddress][this._feeTokenAddress],
+            'Checking right fee receipient ingress ERC20 account fees',
+        ).to.be.bignumber.equal(
+            expectedERC20BalancesByOwner[signedOrderRight.feeRecipientAddress][this._feeTokenAddress],
+        );
+    }
+} // tslint:disable-line:max-file-line-count
diff --git a/packages/contracts/test/utils/order_utils.ts b/packages/contracts/test/utils/order_utils.ts
index 019f6e74b..444e27c44 100644
--- a/packages/contracts/test/utils/order_utils.ts
+++ b/packages/contracts/test/utils/order_utils.ts
@@ -5,7 +5,7 @@ import { constants } from './constants';
 import { CancelOrder, MatchOrder } from './types';
 
 export const orderUtils = {
-    getPartialAmount(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+    getPartialAmountFloor(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
         const partialAmount = numerator
             .mul(target)
             .div(denominator)
diff --git a/packages/contracts/test/utils/test_with_reference.ts b/packages/contracts/test/utils/test_with_reference.ts
index 599b1eed4..b80be4a6c 100644
--- a/packages/contracts/test/utils/test_with_reference.ts
+++ b/packages/contracts/test/utils/test_with_reference.ts
@@ -6,6 +6,34 @@ import { chaiSetup } from './chai_setup';
 chaiSetup.configure();
 const expect = chai.expect;
 
+class Value<T> {
+    public value: T;
+    constructor(value: T) {
+        this.value = value;
+    }
+}
+
+// tslint:disable-next-line: max-classes-per-file
+class ErrorMessage {
+    public error: string;
+    constructor(message: string) {
+        this.error = message;
+    }
+}
+
+type PromiseResult<T> = Value<T> | ErrorMessage;
+
+// TODO(albrow): This seems like a generic utility function that could exist in
+// lodash. We should replace it by a library implementation, or move it to our
+// own.
+async function evaluatePromise<T>(promise: Promise<T>): Promise<PromiseResult<T>> {
+    try {
+        return new Value<T>(await promise);
+    } catch (e) {
+        return new ErrorMessage(e.message);
+    }
+}
+
 export async function testWithReferenceFuncAsync<P0, R>(
     referenceFunc: (p0: P0) => Promise<R>,
     testFunc: (p0: P0) => Promise<R>,
@@ -64,39 +92,31 @@ export async function testWithReferenceFuncAsync(
     testFuncAsync: (...args: any[]) => Promise<any>,
     values: any[],
 ): Promise<void> {
-    let expectedResult: any;
-    let expectedErr: string | undefined;
-    try {
-        expectedResult = await referenceFuncAsync(...values);
-    } catch (e) {
-        expectedErr = e.message;
-    }
-    let actualResult: any | undefined;
-    try {
-        actualResult = await testFuncAsync(...values);
-        if (!_.isUndefined(expectedErr)) {
+    // Measure correct behaviour
+    const expected = await evaluatePromise(referenceFuncAsync(...values));
+
+    // Measure actual behaviour
+    const actual = await evaluatePromise(testFuncAsync(...values));
+
+    // Compare behaviour
+    if (expected instanceof ErrorMessage) {
+        // If we expected an error, check if the actual error message contains the
+        // expected error message.
+        if (!(actual instanceof ErrorMessage)) {
             throw new Error(
-                `Expected error containing ${expectedErr} but got no error\n\tTest case: ${_getTestCaseString(
+                `Expected error containing ${expected.error} but got no error\n\tTest case: ${_getTestCaseString(
                     referenceFuncAsync,
                     values,
                 )}`,
             );
         }
-    } catch (e) {
-        if (_.isUndefined(expectedErr)) {
-            throw new Error(`${e.message}\n\tTest case: ${_getTestCaseString(referenceFuncAsync, values)}`);
-        } else {
-            expect(e.message).to.contain(
-                expectedErr,
-                `${e.message}\n\tTest case: ${_getTestCaseString(referenceFuncAsync, values)}`,
-            );
-        }
-    }
-    if (!_.isUndefined(actualResult) && !_.isUndefined(expectedResult)) {
-        expect(actualResult).to.deep.equal(
-            expectedResult,
-            `Test case: ${_getTestCaseString(referenceFuncAsync, values)}`,
+        expect(actual.error).to.contain(
+            expected.error,
+            `${actual.error}\n\tTest case: ${_getTestCaseString(referenceFuncAsync, values)}`,
         );
+    } else {
+        // If we do not expect an error, compare actual and expected directly.
+        expect(actual).to.deep.equal(expected, `Test case ${_getTestCaseString(referenceFuncAsync, values)}`);
     }
 }
 
diff --git a/packages/contracts/test/utils/types.ts b/packages/contracts/test/utils/types.ts
index 481ee87d6..598fb5393 100644
--- a/packages/contracts/test/utils/types.ts
+++ b/packages/contracts/test/utils/types.ts
@@ -117,21 +117,24 @@ export interface TransferAmountsByMatchOrders {
     // Left Maker
     amountBoughtByLeftMaker: BigNumber;
     amountSoldByLeftMaker: BigNumber;
-    amountReceivedByLeftMaker: BigNumber;
     feePaidByLeftMaker: BigNumber;
     // Right Maker
     amountBoughtByRightMaker: BigNumber;
     amountSoldByRightMaker: BigNumber;
-    amountReceivedByRightMaker: BigNumber;
     feePaidByRightMaker: BigNumber;
     // Taker
     amountReceivedByTaker: BigNumber;
     feePaidByTakerLeft: BigNumber;
     feePaidByTakerRight: BigNumber;
-    totalFeePaidByTaker: BigNumber;
-    // Fee Recipients
-    feeReceivedLeft: BigNumber;
-    feeReceivedRight: BigNumber;
+}
+
+export interface TransferAmountsLoggedByMatchOrders {
+    makerAddress: string;
+    takerAddress: string;
+    makerAssetFilledAmount: string;
+    takerAssetFilledAmount: string;
+    makerFeePaid: string;
+    takerFeePaid: string;
 }
 
 export interface OrderInfo {
diff --git a/packages/contracts/test/utils_test/test_with_reference.ts b/packages/contracts/test/utils_test/test_with_reference.ts
new file mode 100644
index 000000000..8d633cd1f
--- /dev/null
+++ b/packages/contracts/test/utils_test/test_with_reference.ts
@@ -0,0 +1,63 @@
+import * as chai from 'chai';
+
+import { chaiSetup } from '../utils/chai_setup';
+import { testWithReferenceFuncAsync } from '../utils/test_with_reference';
+
+chaiSetup.configure();
+const expect = chai.expect;
+
+async function divAsync(x: number, y: number): Promise<number> {
+    if (y === 0) {
+        throw new Error('MathError: divide by zero');
+    }
+    return x / y;
+}
+
+// returns an async function that always returns the given value.
+function alwaysValueFunc(value: number): (x: number, y: number) => Promise<number> {
+    return async (x: number, y: number) => value;
+}
+
+// returns an async function which always throws/rejects with the given error
+// message.
+function alwaysFailFunc(errMessage: string): (x: number, y: number) => Promise<number> {
+    return async (x: number, y: number) => {
+        throw new Error(errMessage);
+    };
+}
+
+describe('testWithReferenceFuncAsync', () => {
+    it('passes when both succeed and actual === expected', async () => {
+        await testWithReferenceFuncAsync(alwaysValueFunc(0.5), divAsync, [1, 2]);
+    });
+
+    it('passes when both fail and actual error contains expected error', async () => {
+        await testWithReferenceFuncAsync(alwaysFailFunc('divide by zero'), divAsync, [1, 0]);
+    });
+
+    it('fails when both succeed and actual !== expected', async () => {
+        expect(testWithReferenceFuncAsync(alwaysValueFunc(3), divAsync, [1, 2])).to.be.rejectedWith(
+            'Test case {"x":1,"y":2}: expected { value: 0.5 } to deeply equal { value: 3 }',
+        );
+    });
+
+    it('fails when both fail and actual error does not contain expected error', async () => {
+        expect(
+            testWithReferenceFuncAsync(alwaysFailFunc('Unexpected math error'), divAsync, [1, 0]),
+        ).to.be.rejectedWith(
+            'MathError: divide by zero\n\tTest case: {"x":1,"y":0}: expected \'MathError: divide by zero\' to include \'Unexpected math error\'',
+        );
+    });
+
+    it('fails when referenceFunc succeeds and testFunc fails', async () => {
+        expect(testWithReferenceFuncAsync(alwaysValueFunc(0), divAsync, [1, 0])).to.be.rejectedWith(
+            'Test case {"x":1,"y":0}: expected { error: \'MathError: divide by zero\' } to deeply equal { value: 0 }',
+        );
+    });
+
+    it('fails when referenceFunc fails and testFunc succeeds', async () => {
+        expect(testWithReferenceFuncAsync(alwaysFailFunc('divide by zero'), divAsync, [1, 2])).to.be.rejectedWith(
+            'Expected error containing divide by zero but got no error\n\tTest case: {"x":1,"y":2}',
+        );
+    });
+});